diff --git a/resend/exceptions.py b/resend/exceptions.py
index 41af790..4ceba35 100644
--- a/resend/exceptions.py
+++ b/resend/exceptions.py
@@ -199,6 +199,8 @@ def __init__(
 ERRORS: Dict[str, Dict[str, Any]] = {
     "400": {"validation_error": ValidationError},
     "422": {
+        # API docs use singular `missing_required_field`; keep plural as alias.
+        "missing_required_field": MissingRequiredFieldsError,
         "missing_required_fields": MissingRequiredFieldsError,
         "validation_error": ValidationError,
     },
@@ -232,7 +234,8 @@ def raise_for_code_and_type(
             or
         ValidationError: If the error type is validation_error
             or
-        MissingRequiredFieldsError: If the error type is missing_required_fields
+        MissingRequiredFieldsError: If the error type is missing_required_field
+            (or legacy missing_required_fields)
             or
         MissingApiKeyError: If the error type is missing_api_key
             or
diff --git a/tests/exceptions_test.py b/tests/exceptions_test.py
index 39256ee..91de8bf 100644
--- a/tests/exceptions_test.py
+++ b/tests/exceptions_test.py
@@ -3,7 +3,8 @@
 import pytest
 
 from resend.exceptions import (ApplicationError, MissingApiKeyError,
-                               RateLimitError, ResendError, ValidationError,
+                               MissingRequiredFieldsError, RateLimitError,
+                               ResendError, ValidationError,
                                raise_for_code_and_type)
 
 
@@ -23,6 +24,23 @@ def test_validation_error_from_422(self) -> None:
             raise_for_code_and_type(422, "validation_error", "err")
         assert e.type is ValidationError
 
+    def test_missing_required_field_singular(self) -> None:
+        # Resend API docs use singular `missing_required_field`.
+        with pytest.raises(MissingRequiredFieldsError) as e:
+            raise_for_code_and_type(422, "missing_required_field", "Missing `to` field")
+        assert e.type is MissingRequiredFieldsError
+        assert e.value.error_type == "missing_required_field"
+        assert e.value.code == 422
+
+    def test_missing_required_fields_plural_alias(self) -> None:
+        # Keep plural as a backward-compatible alias.
+        with pytest.raises(MissingRequiredFieldsError) as e:
+            raise_for_code_and_type(
+                422, "missing_required_fields", "Missing `to` field"
+            )
+        assert e.type is MissingRequiredFieldsError
+        assert e.value.error_type == "missing_required_fields"
+
     def test_validation_error_from_400(self) -> None:
         with pytest.raises(ValidationError) as e:
             raise_for_code_and_type(400, "validation_error", "err")