diff --git a/python/langsmith/client.py b/python/langsmith/client.py
index 5db801a64..eefdf936c 100644
--- a/python/langsmith/client.py
+++ b/python/langsmith/client.py
@@ -12,6 +12,7 @@
 import logging
 import os
 import random
+import re
 import socket
 import sys
 import threading
@@ -165,6 +166,19 @@ def _default_retry_config() -> Retry:
 _MAX_DEPTH = 2
 
 
+def _simple_default(obj: Any) -> Any:
+    # Don't traverse into nested objects
+    try:
+        if isinstance(obj, datetime.datetime):
+            return obj.isoformat()
+        if isinstance(obj, uuid.UUID):
+            return str(obj)
+        return json.loads(json.dumps(obj))
+    except BaseException as e:
+        logger.debug(f"Failed to serialize {type(obj)} to JSON: {e}")
+        return repr(obj)
+
+
 def _serialize_json(obj: Any, depth: int = 0, serialize_py: bool = True) -> Any:
     try:
         if depth >= _MAX_DEPTH:
@@ -222,17 +236,37 @@ def _serialize_json(obj: Any, depth: int = 0, serialize_py: bool = True) -> Any:
         return repr(obj)
 
 
+def _elide_surrogates(s: bytes) -> bytes:
+    pattern = re.compile(rb"\\ud[89a-f][0-9a-f]{2}", re.IGNORECASE)
+    result = pattern.sub(b"", s)
+    return result
+
+
 def _dumps_json_single(
     obj: Any, default: Optional[Callable[[Any], Any]] = None
 ) -> bytes:
-    return orjson.dumps(
-        obj,
-        default=default,
-        option=orjson.OPT_SERIALIZE_NUMPY
-        | orjson.OPT_SERIALIZE_DATACLASS
-        | orjson.OPT_SERIALIZE_UUID
-        | orjson.OPT_NON_STR_KEYS,
-    )
+    try:
+        return orjson.dumps(
+            obj,
+            default=default,
+            option=orjson.OPT_SERIALIZE_NUMPY
+            | orjson.OPT_SERIALIZE_DATACLASS
+            | orjson.OPT_SERIALIZE_UUID
+            | orjson.OPT_NON_STR_KEYS,
+        )
+    except TypeError as e:
+        # Usually caused by UTF surrogate characters
+        logger.debug(f"Orjson serialization failed: {repr(e)}. Falling back to json.")
+        result = json.dumps(
+            obj,
+            default=_simple_default,
+            ensure_ascii=True,
+        ).encode("utf-8")
+        try:
+            result = orjson.dumps(orjson.loads(result.decode("utf-8", errors="lossy")))
+        except orjson.JSONDecodeError:
+            result = _elide_surrogates(result)
+        return result
 
 
 def _dumps_json(obj: Any, depth: int = 0, serialize_py: bool = True) -> bytes:
diff --git a/python/tests/integration_tests/test_client.py b/python/tests/integration_tests/test_client.py
index 1bf53af33..4ff1a6afc 100644
--- a/python/tests/integration_tests/test_client.py
+++ b/python/tests/integration_tests/test_client.py
@@ -5,6 +5,7 @@
 import os
 import random
 import string
+import sys
 import time
 from datetime import timedelta
 from typing import Any, Callable, Dict, cast
@@ -12,7 +13,6 @@
 
 import pytest
 from freezegun import freeze_time
-from langchain.schema import FunctionMessage, HumanMessage
 
 from langsmith.client import ID_TYPE, Client
 from langsmith.schemas import DataType
@@ -299,6 +299,8 @@ def test_create_run_with_masked_inputs_outputs(
 def test_create_chat_example(
     monkeypatch: pytest.MonkeyPatch, langchain_client: Client
 ) -> None:
+    from langchain.schema import FunctionMessage, HumanMessage
+
     dataset_name = "__createChatExample-test-dataset"
     try:
         existing_dataset = langchain_client.read_dataset(dataset_name=dataset_name)
@@ -489,3 +491,39 @@ def _get_run(run_id: ID_TYPE, has_end: bool = False) -> bool:
     else:
         assert updated_run.tags == ["tag1", "tag2"]
     assert updated_run.extra["runtime"] == created_run.extra["runtime"]  # type: ignore
+
+
+def test_surrogates():
+    chars = "".join(chr(cp) for cp in range(0, sys.maxunicode + 1))
+    trans_table = str.maketrans("", "", "")
+    all_chars = chars.translate(trans_table)
+    langchain_client = Client()
+    langchain_client.create_run(
+        name="test_run",
+        inputs={
+            "text": [
+                "Hello\ud83d\ude00",
+                "Python\ud83d\udc0d",
+                "Surrogate\ud834\udd1e",
+                "Example\ud83c\udf89",
+                "String\ud83c\udfa7",
+                "With\ud83c\udf08",
+                "Surrogates\ud83d\ude0e",
+                "Embedded\ud83d\udcbb",
+                "In\ud83c\udf0e",
+                "The\ud83d\udcd6",
+                "Text\ud83d\udcac",
+                "收花🙄·到",
+            ]
+        },
+        run_type="llm",
+        end_time=datetime.datetime.now(datetime.timezone.utc),
+    )
+    langchain_client.create_run(
+        name="test_run",
+        inputs={
+            "text": all_chars,
+        },
+        run_type="llm",
+        end_time=datetime.datetime.now(datetime.timezone.utc),
+    )
diff --git a/python/tests/unit_tests/test_client.py b/python/tests/unit_tests/test_client.py
index 95c1cb7b9..36e2e4922 100644
--- a/python/tests/unit_tests/test_client.py
+++ b/python/tests/unit_tests/test_client.py
@@ -7,6 +7,7 @@
 import json
 import math
 import os
+import sys
 import threading
 import time
 import uuid
@@ -766,6 +767,18 @@ class MyNamedTuple(NamedTuple):
             raise
 
 
+def test__dumps_json():
+    chars = "".join(chr(cp) for cp in range(0, sys.maxunicode + 1))
+    trans_table = str.maketrans("", "", "")
+    all_chars = chars.translate(trans_table)
+    serialized_json = _dumps_json({"chars": all_chars})
+    assert isinstance(serialized_json, bytes)
+    serialized_str = serialized_json.decode("utf-8")
+    assert '"chars"' in serialized_str
+    assert "\\uD800" not in serialized_str
+    assert "\\uDC00" not in serialized_str
+
+
 @patch("langsmith.client.requests.Session", autospec=True)
 def test_host_url(_: MagicMock) -> None:
     client = Client(api_url="https://api.foobar.com/api", api_key="API_KEY")