diff --git a/src/agents/retry.py b/src/agents/retry.py
index f240a2d923..4b122cbfa7 100644
--- a/src/agents/retry.py
+++ b/src/agents/retry.py
@@ -16,13 +16,13 @@
 class ModelRetryBackoffSettings:
     """Backoff configuration for runner-managed model retries."""
 
-    initial_delay: float | None = None
+    initial_delay: float | None = Field(default=None, ge=0)
     """Delay in seconds before the first retry attempt."""
 
-    max_delay: float | None = None
+    max_delay: float | None = Field(default=None, ge=0)
     """Maximum delay in seconds between retry attempts."""
 
-    multiplier: float | None = None
+    multiplier: float | None = Field(default=None, ge=0)
     """Multiplier applied after each retry attempt."""
 
     jitter: bool | None = None
diff --git a/tests/models/test_model_retry.py b/tests/models/test_model_retry.py
index 5a99efd282..04b9b1dc9c 100644
--- a/tests/models/test_model_retry.py
+++ b/tests/models/test_model_retry.py
@@ -7,6 +7,7 @@
 import httpx
 import pytest
 from openai import APIConnectionError, APIStatusError, BadRequestError
+from pydantic import ValidationError
 
 from agents.items import ModelResponse, TResponseStreamEvent
 from agents.models._openai_retry import get_openai_retry_advice
@@ -28,6 +29,32 @@
 from tests.test_responses import get_text_message
 
 
+@pytest.mark.parametrize(
+    "make_backoff",
+    [
+        lambda: ModelRetryBackoffSettings(initial_delay=-0.1),
+        lambda: ModelRetryBackoffSettings(max_delay=-0.1),
+        lambda: ModelRetryBackoffSettings(multiplier=-0.1),
+    ],
+)
+def test_model_retry_backoff_settings_reject_negative_values(make_backoff: Any) -> None:
+    with pytest.raises(ValidationError, match="greater than or equal to 0"):
+        make_backoff()
+
+
+def test_model_retry_settings_rejects_negative_backoff_dict() -> None:
+    with pytest.raises(ValidationError, match="greater than or equal to 0"):
+        ModelRetrySettings(backoff={"initial_delay": -0.1})
+
+
+def test_model_retry_backoff_settings_allow_zero_values() -> None:
+    backoff = ModelRetryBackoffSettings(initial_delay=0, max_delay=0, multiplier=0)
+
+    assert backoff.initial_delay == 0
+    assert backoff.max_delay == 0
+    assert backoff.multiplier == 0
+
+
 def _connection_error(message: str = "connection error") -> APIConnectionError:
     return APIConnectionError(
         message=message,