diff --git a/pydantic_ai_slim/pydantic_ai/models/openai.py b/pydantic_ai_slim/pydantic_ai/models/openai.py
index bb8aadcf92..0371f7593f 100644
--- a/pydantic_ai_slim/pydantic_ai/models/openai.py
+++ b/pydantic_ai_slim/pydantic_ai/models/openai.py
@@ -74,6 +74,7 @@
     'OpenAIModelSettings',
     'OpenAIResponsesModelSettings',
     'OpenAIModelName',
+    'OpenAISystemPromptRole',
 )
 
 OpenAIModelName = Union[str, ChatModel]
diff --git a/pydantic_ai_slim/pydantic_ai/models/openrouter.py b/pydantic_ai_slim/pydantic_ai/models/openrouter.py
new file mode 100644
index 0000000000..8998adae27
--- /dev/null
+++ b/pydantic_ai_slim/pydantic_ai/models/openrouter.py
@@ -0,0 +1,105 @@
+from typing import Any, Literal, overload
+
+from openai import AsyncStream
+from openai.types.chat import ChatCompletion, ChatCompletionChunk
+from pydantic import BaseModel
+
+from .. import ModelHTTPError
+from ..messages import ModelMessage, ModelResponse
+from ..profiles import ModelProfileSpec
+from ..providers.openrouter import OpenRouterProvider
+from . import ModelRequestParameters
+from .openai import OpenAIModel, OpenAIModelName, OpenAIModelSettings, OpenAISystemPromptRole
+
+
+class OpenRouterErrorResponse(BaseModel):
+    """Represents error responses from upstream LLM provider relayed by OpenRouter.
+
+    Attributes:
+        code: The error code returned by LLM provider.
+        message: The error message returned by OpenRouter
+        metadata: Additional error context provided by OpenRouter.
+
+    See: https://openrouter.ai/docs/api-reference/errors
+    """
+
+    code: int
+    message: str
+    metadata: dict[str, Any] | None
+
+
+class OpenRouterChatCompletion(ChatCompletion):
+    """Extends ChatCompletion with OpenRouter-specific attributes.
+
+    This class extends the base ChatCompletion model to include additional
+    fields returned specifically by the OpenRouter API.
+
+    Attributes:
+        provider: The name of the upstream LLM provider (e.g., "Anthropic",
+            "OpenAI", etc.) that processed the request through OpenRouter.
+    """
+
+    provider: str
+
+
+class OpenRouterModel(OpenAIModel):
+    """Extends OpenAIModel to capture extra metadata for Openrouter."""
+
+    def __init__(
+        self,
+        model_name: OpenAIModelName,
+        *,
+        provider: Literal['openrouter'] | OpenRouterProvider = 'openrouter',
+        profile: ModelProfileSpec | None = None,
+        system_prompt_role: OpenAISystemPromptRole | None = None,
+    ):
+        super().__init__(model_name, provider=provider, profile=profile, system_prompt_role=system_prompt_role)
+
+    @overload
+    async def _completions_create(
+        self,
+        messages: list[ModelMessage],
+        stream: Literal[True],
+        model_settings: OpenAIModelSettings,
+        model_request_parameters: ModelRequestParameters,
+    ) -> AsyncStream[ChatCompletionChunk]: ...
+
+    @overload
+    async def _completions_create(
+        self,
+        messages: list[ModelMessage],
+        stream: Literal[False],
+        model_settings: OpenAIModelSettings,
+        model_request_parameters: ModelRequestParameters,
+    ) -> ChatCompletion: ...
+
+    async def _completions_create(
+        self,
+        messages: list[ModelMessage],
+        stream: bool,
+        model_settings: OpenAIModelSettings,
+        model_request_parameters: ModelRequestParameters,
+    ) -> ChatCompletion | AsyncStream[ChatCompletionChunk]:
+        response = await super()._completions_create(
+            messages=messages,
+            stream=stream,
+            model_settings=model_settings,
+            model_request_parameters=model_request_parameters,
+        )
+        if error := getattr(response, 'error', None):
+            parsed_error = OpenRouterErrorResponse.model_validate(error)
+            raise ModelHTTPError(
+                status_code=parsed_error.code, model_name=self.model_name, body=parsed_error.model_dump()
+            )
+        else:
+            return response
+
+    def _process_response(self, response: ChatCompletion) -> ModelResponse:
+        response = OpenRouterChatCompletion.construct(**response.model_dump())
+        model_response = super()._process_response(response=response)
+        openrouter_provider: str | None = getattr(response, 'provider', None)
+        if openrouter_provider:
+            vendor_details: dict[str, Any] = model_response.vendor_details or {}
+            vendor_details['provider'] = openrouter_provider
+            model_response.vendor_details = vendor_details
+        return model_response
diff --git a/tests/models/cassettes/test_openrouter/test_openrouter_errors_raised.yaml b/tests/models/cassettes/test_openrouter/test_openrouter_errors_raised.yaml
new file mode 100644
index 0000000000..b54b0ceb54
--- /dev/null
+++ b/tests/models/cassettes/test_openrouter/test_openrouter_errors_raised.yaml
@@ -0,0 +1,50 @@
+interactions:
+- request:
+    headers:
+      accept:
+      - application/json
+      accept-encoding:
+      - gzip, deflate
+      connection:
+      - keep-alive
+      content-length:
+      - '164'
+      content-type:
+      - application/json
+      host:
+      - openrouter.ai
+    method: POST
+    parsed_body:
+      messages:
+      - content: Be helpful.
+        role: system
+      - content: Tell me a joke.
+        role: user
+      model: google/gemini-2.0-flash-exp:free
+      n: 1
+      stream: false
+    uri: https://openrouter.ai/api/v1/chat/completions
+  response:
+    headers:
+      access-control-allow-origin:
+      - '*'
+      connection:
+      - keep-alive
+      content-length:
+      - '242'
+      content-type:
+      - application/json
+      vary:
+      - Accept-Encoding
+    parsed_body:
+      error:
+        code: 429  # Upstream LLM provider error
+        message: Provider returned error
+        metadata:
+          provider_name: Google
+          raw: google/gemini-2.0-flash-exp:free is temporarily rate-limited upstream; please retry shortly.
+      user_id: user_2uRh0l3Yi3hdjBArTOSmLXWJBc4
+    status:
+      code: 200  # Openrouter returns 200 OK
+      message: OK
+version: 1
diff --git a/tests/models/test_openrouter.py b/tests/models/test_openrouter.py
new file mode 100644
index 0000000000..8e4777ea8a
--- /dev/null
+++ b/tests/models/test_openrouter.py
@@ -0,0 +1,27 @@
+import pytest
+from inline_snapshot import snapshot
+
+from pydantic_ai import Agent, ModelHTTPError
+
+from ..conftest import try_import
+
+with try_import() as imports_successful:
+    from pydantic_ai.models.openrouter import OpenRouterModel
+    from pydantic_ai.providers.openrouter import OpenRouterProvider
+
+pytestmark = [
+    pytest.mark.skipif(not imports_successful(), reason='openai not installed'),
+    pytest.mark.vcr,
+    pytest.mark.anyio,
+]
+
+
+async def test_openrouter_errors_raised(allow_model_requests: None, openrouter_api_key: str) -> None:
+    provider = OpenRouterProvider(api_key=openrouter_api_key)
+    model = OpenRouterModel('google/gemini-2.0-flash-exp:free', provider=provider)
+    agent = Agent(model, instructions='Be helpful.', retries=1)
+    with pytest.raises(ModelHTTPError) as exc_info:
+        await agent.run('Tell me a joke.')
+    assert str(exc_info.value) == snapshot(
+        "status_code: 429, model_name: google/gemini-2.0-flash-exp:free, body: {'code': 429, 'message': 'Provider returned error', 'metadata': {'provider_name': 'Google', 'raw': 'google/gemini-2.0-flash-exp:free is temporarily rate-limited upstream; please retry shortly.'}}"
+    )
diff --git a/tests/providers/test_openrouter.py b/tests/providers/test_openrouter.py
index 0780c8211e..7cbd9aff3d 100644
--- a/tests/providers/test_openrouter.py
+++ b/tests/providers/test_openrouter.py
@@ -7,6 +7,7 @@
 
 from pydantic_ai.agent import Agent
 from pydantic_ai.exceptions import UserError
+from pydantic_ai.messages import ModelRequest, ModelResponse, TextPart, UserPromptPart
 from pydantic_ai.profiles._json_schema import InlineDefsJsonSchemaTransformer
 from pydantic_ai.profiles.amazon import amazon_model_profile
 from pydantic_ai.profiles.anthropic import anthropic_model_profile
@@ -18,13 +19,14 @@
 from pydantic_ai.profiles.mistral import mistral_model_profile
 from pydantic_ai.profiles.openai import OpenAIJsonSchemaTransformer, openai_model_profile
 from pydantic_ai.profiles.qwen import qwen_model_profile
+from pydantic_ai.usage import Usage
 
-from ..conftest import TestEnv, try_import
+from ..conftest import IsDatetime, IsStr, TestEnv, try_import
 
 with try_import() as imports_successful:
     import openai
 
-    from pydantic_ai.models.openai import OpenAIModel
+    from pydantic_ai.models.openrouter import OpenRouterModel
     from pydantic_ai.providers.openrouter import OpenRouterProvider
 
 
@@ -69,8 +71,8 @@ def test_openrouter_pass_openai_client() -> None:
 
 async def test_openrouter_with_google_model(allow_model_requests: None, openrouter_api_key: str) -> None:
     provider = OpenRouterProvider(api_key=openrouter_api_key)
-    model = OpenAIModel('google/gemini-2.0-flash-exp:free', provider=provider)
-    agent = Agent(model, instructions='Be helpful.')
+    model = OpenRouterModel('google/gemini-2.0-flash-exp:free', provider=provider)
+    agent = Agent(model, instructions='Be helpful.', retries=1)
     response = await agent.run('Tell me a joke.')
     assert response.output == snapshot("""\
 Why don't scientists trust atoms? \n\
@@ -78,6 +80,36 @@ async def test_openrouter_with_google_model(allow_model_requests: None, openrout
 Because they make up everything!
 """)
 
+    assert response.all_messages() == snapshot(
+        [
+            ModelRequest(
+                parts=[
+                    UserPromptPart(
+                        content='Tell me a joke.',
+                        timestamp=IsDatetime(iso_string=True),
+                    )
+                ],
+                instructions='Be helpful.',
+            ),
+            ModelResponse(
+                parts=[
+                    TextPart(
+                        content="""\
+Why don't scientists trust atoms? \n\
+
+Because they make up everything!
+"""
+                    )
+                ],
+                usage=Usage(requests=1, request_tokens=8, response_tokens=17, total_tokens=25, details={}),
+                model_name='google/gemini-2.0-flash-exp:free',
+                timestamp=IsDatetime(iso_string=True),
+                vendor_details={'provider': 'Google'},
+                vendor_id=IsStr(),
+            ),
+        ]
+    )
+
 
 def test_openrouter_provider_model_profile(mocker: MockerFixture):
     provider = OpenRouterProvider(api_key='api-key')