diff --git a/src/anthropic/lib/bedrock/_client.py b/src/anthropic/lib/bedrock/_client.py
index cda0690df..644beea9c 100644
--- a/src/anthropic/lib/bedrock/_client.py
+++ b/src/anthropic/lib/bedrock/_client.py
@@ -3,7 +3,7 @@
 import os
 import logging
 import urllib.parse
-from typing import Any, Union, Mapping, TypeVar
+from typing import Any, Dict, Union, Mapping, TypeVar, cast
 from typing_extensions import Self, override
 
 import httpx
@@ -35,6 +35,23 @@
 _DefaultStreamT = TypeVar("_DefaultStreamT", bound=Union[Stream[Any], AsyncStream[Any]])
 
 
+def _strip_none_values(data: Dict[str, object]) -> Dict[str, object]:
+    result: Dict[str, object] = {}
+    for k, v in data.items():
+        if v is None:
+            continue
+        if isinstance(v, dict):
+            result[k] = _strip_none_values(cast(Dict[str, object], v))
+        elif isinstance(v, list):
+            result[k] = [
+                _strip_none_values(cast(Dict[str, object], item)) if isinstance(item, dict) else item
+                for item in cast("list[object]", v)
+            ]
+        else:
+            result[k] = v
+    return result
+
+
 def _prepare_options(input_options: FinalRequestOptions) -> FinalRequestOptions:
     options = model_copy(input_options, deep=True)
 
@@ -46,6 +63,17 @@ def _prepare_options(input_options: FinalRequestOptions) -> FinalRequestOptions:
             if betas:
                 options.json_data.setdefault("anthropic_beta", betas.split(","))
 
+        messages = options.json_data.get("messages")
+        if isinstance(messages, list):
+            for message in cast("list[object]", messages):
+                if is_dict(message):
+                    content = message.get("content")
+                    if isinstance(content, list):
+                        message["content"] = [
+                            _strip_none_values(cast(Dict[str, object], block)) if is_dict(block) else block
+                            for block in cast("list[object]", content)
+                        ]
+
     if options.url in {"/v1/complete", "/v1/messages", "/v1/messages?beta=true"} and options.method == "post":
         if not is_dict(options.json_data):
             raise RuntimeError("Expected dictionary json_data for post /completions endpoint")
diff --git a/tests/lib/test_bedrock.py b/tests/lib/test_bedrock.py
index 6e45c27f7..1c3847c2e 100644
--- a/tests/lib/test_bedrock.py
+++ b/tests/lib/test_bedrock.py
@@ -275,3 +275,52 @@ def test_region_infer_from_specified_profile(
     client = AnthropicBedrock()
 
     assert client.aws_region == next(profile for profile in profiles if profile["name"] == aws_profile)["region"]
+
+
+@pytest.mark.filterwarnings("ignore::DeprecationWarning")
+@pytest.mark.respx()
+def test_none_values_stripped_from_content_blocks(respx_mock: MockRouter) -> None:
+    """ToolUseBlock.caller is Optional[Caller] = None in responses but
+    ToolUseBlockParam.caller expects a valid Caller dict when present.
+    Bedrock rejects {"caller": null}, so _prepare_options must strip it."""
+    import json
+
+    respx_mock.post(re.compile(r"https://bedrock-runtime\.us-east-1\.amazonaws\.com/model/.*/invoke")).mock(
+        return_value=httpx.Response(200, json={"foo": "bar"}),
+    )
+
+    sync_client.messages.create(
+        max_tokens=1024,
+        messages=[
+            {
+                "role": "assistant",
+                "content": [
+                    {
+                        "type": "tool_use",
+                        "id": "toolu_01A",
+                        "name": "get_weather",
+                        "input": {"location": "Paris"},
+                        "caller": None,
+                    }
+                ],
+            },
+            {
+                "role": "user",
+                "content": [
+                    {
+                        "type": "tool_result",
+                        "tool_use_id": "toolu_01A",
+                        "content": "Sunny, 22°C",
+                    }
+                ],
+            },
+        ],
+        model="anthropic.claude-3-5-sonnet-20241022-v2:0",
+    )
+
+    calls = cast("list[MockRequestCall]", respx_mock.calls)
+    assert len(calls) == 1
+
+    body = json.loads(calls[0].request.content)
+    tool_use_block = body["messages"][0]["content"][0]
+    assert "caller" not in tool_use_block