diff --git a/CHANGELOG.md b/CHANGELOG.md
index 90a4cdc..76f0e83 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
+- ISSN (International Standard Serial Number) validation: `it.IsISSN()`, `validate.ISSN`, `is.ISSN`, with `validation.ErrInvalidISSN` / `message.InvalidISSN` and English and Russian translations (ISO 3297 mod 11 check digit; optional hyphen; behavior aligned with Symfony `Issn`).
 - BIC / SWIFT validation: `it.IsBIC()` with `CaseInsensitive` and `WithIBAN` (and `WithIBANError` / `WithIBANMessage`), `validate.BIC` with `validate.BICCaseInsensitive` and `validate.BICWithIBAN`, `is.BIC`; `validation.ErrInvalidBIC`, `validation.ErrBICIBANCountryMismatch`, `message.InvalidBIC`, `message.BICNotAssociatedWithIBAN` and English and Russian translations (behavior aligned with Symfony `Bic` / `BicValidator`; country/territory check via `golang.org/x/text/language` regions plus Symfony’s BIC-to-IBAN territory map).
 - IBAN validation: `it.IsIBAN()`, `validate.IBAN`, `is.IBAN`, with `validation.ErrInvalidIBAN` / `message.InvalidIBAN` and English and Russian translations (behavior aligned with Symfony `Iban`; country patterns from Symfony 7.2 `IbanValidator`).
 - **NoSuspiciousCharacters** (spoofing / homoglyph checks): `it.HasNoSuspiciousCharacters()` with `CheckInvisible` / `CheckMixedNumbers` / `CheckHiddenOverlay`, `WithoutInvisible` / `WithoutMixedNumbers` / `WithoutHiddenOverlay` (bitmask-based), locale and single-script restrictions; `validate.NoSuspiciousCharacters`; errors `validation.ErrSuspiciousInvisible`, `ErrSuspiciousMixedNumbers`, `ErrSuspiciousHiddenOverlay`, `ErrSuspiciousCharactersRestriction` and English/Russian messages (behavior inspired by Symfony `NoSuspiciousCharacters`, implemented without CGO; may differ from ICU in edge cases).
diff --git a/errors.go b/errors.go
index f1e2ca7..f38fb4d 100644
--- a/errors.go
+++ b/errors.go
@@ -19,6 +19,7 @@ var (
 	ErrInvalidBIC             = NewError("invalid BIC", message.InvalidBIC)
 	ErrBICIBANCountryMismatch = NewError("BIC IBAN country mismatch", message.BICNotAssociatedWithIBAN)
 	ErrInvalidISIN            = NewError("invalid ISIN", message.InvalidISIN)
+	ErrInvalidISSN            = NewError("invalid ISSN", message.InvalidISSN)
 	ErrInvalidCIDR            = NewError("invalid CIDR", message.InvalidCIDR)
 	ErrCIDRNetmaskOutOfRange  = NewError("CIDR netmask out of range", message.CIDRNetmaskOutOfRange)
 	ErrInvalidIP              = NewError("invalid IP address", message.InvalidIP)
diff --git a/is/example_test.go b/is/example_test.go
index f76cb6c..b658235 100644
--- a/is/example_test.go
+++ b/is/example_test.go
@@ -295,6 +295,20 @@ func ExampleISIN() {
 	// false
 }
 
+func ExampleISSN() {
+	fmt.Println(is.ISSN("0317-8471"))
+	fmt.Println(is.ISSN("03178471"))
+	fmt.Println(is.ISSN("2434-561X"))
+	fmt.Println(is.ISSN("0317-8470"))
+	fmt.Println(is.ISSN("123-45678"))
+	// Output:
+	// true
+	// true
+	// true
+	// false
+	// false
+}
+
 func ExampleLUHN() {
 	fmt.Println(is.LUHN("79927398713"))
 	fmt.Println(is.LUHN("79927398710"))
diff --git a/is/identifiers.go b/is/identifiers.go
index 92ecf77..c672ab5 100644
--- a/is/identifiers.go
+++ b/is/identifiers.go
@@ -32,6 +32,14 @@ func ISIN(value string) bool {
 	return validate.ISIN(value) == nil
 }
 
+// ISSN validates whether the value is a valid International Standard Serial Number (ISSN).
+// See [github.com/muonsoft/validation/validate.ISSN] for validation rules and possible errors.
+//
+// See https://www.issn.org/understanding-the-issn/what-is-an-issn/.
+func ISSN(value string) bool {
+	return validate.ISSN(value) == nil
+}
+
 // LUHN validates whether the value passes the Luhn (mod 10) checksum.
 // See [github.com/muonsoft/validation/validate.LUHN] for validation rules and possible errors.
 //
diff --git a/it/example_test.go b/it/example_test.go
index bfa207b..12cecb7 100644
--- a/it/example_test.go
+++ b/it/example_test.go
@@ -83,6 +83,20 @@ func ExampleIsISIN_invalid() {
 	// violation: "This value is not a valid International Securities Identification Number (ISIN)."
 }
 
+func ExampleIsISSN_valid() {
+	err := validator.Validate(context.Background(), validation.String("0317-8471", it.IsISSN()))
+	fmt.Println(err)
+	// Output:
+	// <nil>
+}
+
+func ExampleIsISSN_invalid() {
+	err := validator.Validate(context.Background(), validation.String("0317-8470", it.IsISSN()))
+	fmt.Println(err)
+	// Output:
+	// violation: "This value is not a valid ISSN."
+}
+
 func ExampleIsLUHN_valid() {
 	err := validator.Validate(context.Background(), validation.String("79927398713", it.IsLUHN()))
 	fmt.Println(err)
diff --git a/it/identifiers.go b/it/identifiers.go
index ac26cf9..c61e53a 100644
--- a/it/identifiers.go
+++ b/it/identifiers.go
@@ -34,6 +34,16 @@ func IsISIN() validation.StringFuncConstraint {
 		WithMessage(validation.ErrInvalidISIN.Message())
 }
 
+// IsISSN validates whether the value is a valid International Standard Serial Number (ISSN).
+// Behavior is aligned with Symfony\Component\Validator\Constraints\Issn.
+//
+// See ISO 3297 and https://www.issn.org/understanding-the-issn/what-is-an-issn/.
+func IsISSN() validation.StringFuncConstraint {
+	return validation.OfStringBy(is.ISSN).
+		WithError(validation.ErrInvalidISSN).
+		WithMessage(validation.ErrInvalidISSN.Message())
+}
+
 // IsLUHN validates whether the value passes the Luhn (mod 10) checksum, as in
 // Symfony\Component\Validator\Constraints\Luhn.
 //
diff --git a/message/messages.go b/message/messages.go
index 1c8e73d..0438f90 100644
--- a/message/messages.go
+++ b/message/messages.go
@@ -37,6 +37,7 @@ const (
 	InvalidBIC               = "This is not a valid Business Identifier Code (BIC)."
 	BICNotAssociatedWithIBAN = "This Business Identifier Code (BIC) is not associated with IBAN {{ iban }}."
 	InvalidISIN              = "This value is not a valid International Securities Identification Number (ISIN)."
+	InvalidISSN              = "This value is not a valid ISSN."
 	InvalidCIDR              = "This value is not a valid CIDR notation."
 	CIDRNetmaskOutOfRange    = "The value of the netmask should be between {{ min }} and {{ max }}."
 	InvalidIP                = "This is not a valid IP address."
diff --git a/message/translations/english/messages.go b/message/translations/english/messages.go
index 417d9ee..5eb9e72 100644
--- a/message/translations/english/messages.go
+++ b/message/translations/english/messages.go
@@ -58,6 +58,7 @@ var Messages = map[language.Tag]map[string]catalog.Message{
 		message.InvalidBIC:               catalog.String(message.InvalidBIC),
 		message.BICNotAssociatedWithIBAN: catalog.String(message.BICNotAssociatedWithIBAN),
 		message.InvalidISIN:              catalog.String(message.InvalidISIN),
+		message.InvalidISSN:              catalog.String(message.InvalidISSN),
 		message.InvalidCIDR:              catalog.String(message.InvalidCIDR),
 		message.CIDRNetmaskOutOfRange:    catalog.String(message.CIDRNetmaskOutOfRange),
 		message.InvalidIP:                catalog.String(message.InvalidIP),
diff --git a/message/translations/russian/messages.go b/message/translations/russian/messages.go
index 3732690..aa17591 100644
--- a/message/translations/russian/messages.go
+++ b/message/translations/russian/messages.go
@@ -61,6 +61,7 @@ var Messages = map[language.Tag]map[string]catalog.Message{
 		message.InvalidBIC:               catalog.String("Значение не является допустимым банковским идентификатором (BIC)."),
 		message.BICNotAssociatedWithIBAN: catalog.String("Этот банковский идентификатор (BIC) не соответствует IBAN {{ iban }}."),
 		message.InvalidISIN:              catalog.String("Значение не является допустимым международным идентификационным номером ценной бумаги (ISIN)."),
+		message.InvalidISSN:              catalog.String("Значение не является допустимым ISSN."),
 		message.InvalidCIDR:              catalog.String("Значение не является допустимой записью CIDR."),
 		message.CIDRNetmaskOutOfRange:    catalog.String("Значение маски сети должно быть между {{ min }} и {{ max }}."),
 		message.InvalidIP:                catalog.String("Значение не является допустимым IP адресом."),
diff --git a/test/constraints_identifiers_cases_test.go b/test/constraints_identifiers_cases_test.go
index fb46d63..af04e11 100644
--- a/test/constraints_identifiers_cases_test.go
+++ b/test/constraints_identifiers_cases_test.go
@@ -12,6 +12,7 @@ var identifierConstraintsTestCases = mergeTestCases(
 	ibanConstraintTestCases,
 	bicConstraintTestCases,
 	isinConstraintTestCases,
+	issnConstraintTestCases,
 	luhnConstraintTestCases,
 )
 
@@ -296,6 +297,86 @@ var isinConstraintTestCases = []ConstraintValidationTestCase{
 	},
 }
 
+var issnConstraintTestCases = []ConstraintValidationTestCase{
+	{
+		name:            "IsISSN passes on empty value",
+		isApplicableFor: specificValueTypes(stringType),
+		constraint:      it.IsISSN(),
+		stringValue:     stringValue(""),
+		assert:          assertNoError,
+	},
+	{
+		name:            "IsISSN passes on valid value with hyphen",
+		isApplicableFor: specificValueTypes(stringType),
+		stringValue:     stringValue("0317-8471"),
+		constraint:      it.IsISSN(),
+		assert:          assertNoError,
+	},
+	{
+		name:            "IsISSN passes on valid value without hyphen",
+		isApplicableFor: specificValueTypes(stringType),
+		stringValue:     stringValue("03178471"),
+		constraint:      it.IsISSN(),
+		assert:          assertNoError,
+	},
+	{
+		name:            "IsISSN passes on check digit X",
+		isApplicableFor: specificValueTypes(stringType),
+		stringValue:     stringValue("2434-561X"),
+		constraint:      it.IsISSN(),
+		assert:          assertNoError,
+	},
+	{
+		name:            "IsISSN passes on lowercase check digit x",
+		isApplicableFor: specificValueTypes(stringType),
+		stringValue:     stringValue("2434-561x"),
+		constraint:      it.IsISSN(),
+		assert:          assertNoError,
+	},
+	{
+		name:            "IsISSN violation on wrong length",
+		isApplicableFor: specificValueTypes(stringType),
+		stringValue:     stringValue("0317-847"),
+		constraint:      it.IsISSN(),
+		assert:          assertHasOneViolation(validation.ErrInvalidISSN, message.InvalidISSN),
+	},
+	{
+		name:            "IsISSN violation on invalid hyphen placement",
+		isApplicableFor: specificValueTypes(stringType),
+		stringValue:     stringValue("123-45678"),
+		constraint:      it.IsISSN(),
+		assert:          assertHasOneViolation(validation.ErrInvalidISSN, message.InvalidISSN),
+	},
+	{
+		name:            "IsISSN violation on invalid checksum",
+		isApplicableFor: specificValueTypes(stringType),
+		stringValue:     stringValue("0317-8470"),
+		constraint:      it.IsISSN(),
+		assert:          assertHasOneViolation(validation.ErrInvalidISSN, message.InvalidISSN),
+	},
+	{
+		name:            "IsISSN passes when condition is false",
+		isApplicableFor: specificValueTypes(stringType),
+		constraint:      it.IsISSN().When(false),
+		stringValue:     stringValue("bad"),
+		assert:          assertNoError,
+	},
+	{
+		name:            "IsISSN violation when condition is true",
+		isApplicableFor: specificValueTypes(stringType),
+		constraint:      it.IsISSN().When(true),
+		stringValue:     stringValue("bad"),
+		assert:          assertHasOneViolation(validation.ErrInvalidISSN, message.InvalidISSN),
+	},
+	{
+		name:            "IsISSN passes when groups not match",
+		isApplicableFor: specificValueTypes(stringType),
+		constraint:      it.IsISSN().WhenGroups(testGroup),
+		stringValue:     stringValue("bad"),
+		assert:          assertNoError,
+	},
+}
+
 var luhnConstraintTestCases = []ConstraintValidationTestCase{
 	{
 		name:            "IsLUHN passes on empty value",
diff --git a/validate/example_test.go b/validate/example_test.go
index 553f829..23631fe 100644
--- a/validate/example_test.go
+++ b/validate/example_test.go
@@ -192,6 +192,18 @@ func ExampleISIN() {
 	// invalid checksum
 }
 
+func ExampleISSN() {
+	fmt.Println(validate.ISSN("0317-8471"))
+	fmt.Println(validate.ISSN("0317-847"))
+	fmt.Println(validate.ISSN("123-45678"))
+	fmt.Println(validate.ISSN("0317-8470"))
+	// Output:
+	// <nil>
+	// too short
+	// invalid characters
+	// invalid checksum
+}
+
 func ExampleLUHN() {
 	fmt.Println(validate.LUHN("79927398713"))
 	fmt.Println(validate.LUHN("79927398710"))
diff --git a/validate/identifiers.go b/validate/identifiers.go
index a9deedc..bc9923c 100644
--- a/validate/identifiers.go
+++ b/validate/identifiers.go
@@ -24,6 +24,9 @@ var ulidChars = newCharSet("0123456789ABCDEFGHJKMNPQRSTVWXYZabcdefghjkmnpqrstvwx
 // Same pattern as Symfony Isin::VALIDATION_PATTERN (length is checked separately).
 var isinPattern = regexp.MustCompile(`^[A-Z]{2}[A-Z0-9]{9}[0-9]$`)
 
+// Same pattern as Symfony Issn::PATTERN (optional hyphen between the two groups).
+var issnPattern = regexp.MustCompile(`^[0-9]{4}-?[0-9]{3}[0-9Xx]$`)
+
 // ULID validates whether the value is a valid ULID (Universally Unique Lexicographically Sortable Identifier).
 // See https://github.com/ulid/spec for ULID specifications.
 //
@@ -85,6 +88,58 @@ func ISIN(value string) error {
 	return nil
 }
 
+// ISSN validates whether the value is a valid International Standard Serial Number (ISSN).
+// The check digit uses the ISO 3297 mod 11 algorithm (weights 8…2 on the first seven digits).
+// An optional hyphen is allowed between the two four-character groups, matching
+// Symfony\Component\Validator\Constraints\Issn.
+//
+// Possible errors:
+//   - [ErrTooShort] when fewer than eight digits/check characters remain after removing hyphens;
+//   - [ErrTooLong] when more than eight remain;
+//   - [ErrInvalidCharacters] when the format is not NNNN-NNNC (with optional hyphen) or digits are invalid;
+//   - [ErrInvalidChecksum] when the check character is wrong;
+//
+// See https://www.issn.org/understanding-the-issn/what-is-an-issn/ and ISO 3297.
+func ISSN(value string) error {
+	if issnPattern.MatchString(value) {
+		return issnValidateBody(strings.ToUpper(strings.ReplaceAll(value, "-", "")))
+	}
+	s := strings.ReplaceAll(value, "-", "")
+	switch {
+	case len(s) < 8:
+		return ErrTooShort
+	case len(s) > 8:
+		return ErrTooLong
+	default:
+		return ErrInvalidCharacters
+	}
+}
+
+func issnValidateBody(canonical string) error {
+	var sum int
+	for i := 0; i < 7; i++ {
+		c := canonical[i]
+		if c < '0' || c > '9' {
+			return ErrInvalidCharacters
+		}
+		sum += int(c-'0') * (8 - i)
+	}
+	check := 11 - (sum % 11)
+	if check == 11 {
+		check = 0
+	}
+	var expected byte
+	if check < 10 {
+		expected = byte('0' + check)
+	} else {
+		expected = 'X'
+	}
+	if canonical[7] != expected {
+		return ErrInvalidChecksum
+	}
+	return nil
+}
+
 func isinCharValue(c byte) int {
 	switch {
 	case c >= '0' && c <= '9':
diff --git a/validate/identifiers_test.go b/validate/identifiers_test.go
index 127ea8f..679b297 100644
--- a/validate/identifiers_test.go
+++ b/validate/identifiers_test.go
@@ -7,6 +7,36 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
+func TestISSN(t *testing.T) {
+	tests := []struct {
+		value         string
+		expectedError error
+	}{
+		{value: "0317-8471"},
+		{value: "03178471"},
+		{value: "2434-561X"},
+		{value: "2434-561x"},
+		{value: "", expectedError: validate.ErrTooShort},
+		{value: "0317-847", expectedError: validate.ErrTooShort},
+		{value: "031784712", expectedError: validate.ErrTooLong},
+		{value: "1234-567890", expectedError: validate.ErrTooLong},
+		{value: "123-45678", expectedError: validate.ErrInvalidCharacters},
+		{value: "1234-567y", expectedError: validate.ErrInvalidCharacters},
+		{value: "0317-8470", expectedError: validate.ErrInvalidChecksum},
+	}
+	for _, test := range tests {
+		t.Run(test.value, func(t *testing.T) {
+			err := validate.ISSN(test.value)
+
+			if test.expectedError == nil {
+				assert.NoError(t, err)
+			} else {
+				assert.ErrorIs(t, err, test.expectedError)
+			}
+		})
+	}
+}
+
 func TestISIN(t *testing.T) {
 	tests := []struct {
 		value         string