diff --git a/ddtrace/contrib/internal/anthropic/utils.py b/ddtrace/contrib/internal/anthropic/utils.py
index 1f383113c86..d662d41a030 100644
--- a/ddtrace/contrib/internal/anthropic/utils.py
+++ b/ddtrace/contrib/internal/anthropic/utils.py
@@ -88,6 +88,10 @@ def tag_params_on_span(span, kwargs, integration):
     for k, v in kwargs.items():
         if k == "system" and integration.is_pc_sampled_span(span):
             span.set_tag_str("anthropic.request.system", integration.trunc(str(v)))
+        elif k == "metadata" and isinstance(v, dict):
+            user_id = _get_attr(v, "user_id", None)
+            if user_id:
+                span.set_tag_str("anthropic.request.user_id", str(user_id))
         elif k not in ("messages", "model"):
             tagged_params[k] = v
     span.set_tag_str("anthropic.request.parameters", safe_json(tagged_params))
diff --git a/releasenotes/notes/add-userid-tag-anthropic-b842a8cbe209c5f1.yaml b/releasenotes/notes/add-userid-tag-anthropic-b842a8cbe209c5f1.yaml
new file mode 100644
index 00000000000..0af58a7d4e7
--- /dev/null
+++ b/releasenotes/notes/add-userid-tag-anthropic-b842a8cbe209c5f1.yaml
@@ -0,0 +1,4 @@
+---
+features:
+  - |
+    tracing: Add ``anthropic.request.user_id`` tag to Anthropic spans from ``metadata.user_id`` parameter.
diff --git a/tests/contrib/anthropic/test_anthropic.py b/tests/contrib/anthropic/test_anthropic.py
index b77c520710c..6c84320d475 100644
--- a/tests/contrib/anthropic/test_anthropic.py
+++ b/tests/contrib/anthropic/test_anthropic.py
@@ -38,6 +38,22 @@ def test_global_tags(ddtrace_config_anthropic, anthropic, request_vcr, mock_trac
     assert span.get_tag("anthropic.request.api_key") == "sk-...key>"
 
 
+def test_user_id_tag(ddtrace_config_anthropic, anthropic, request_vcr, mock_tracer):
+    llm = anthropic.Anthropic()
+    with override_global_config(dict(service="test-svc", env="staging", version="1234")):
+        cassette_name = "anthropic_completion.yaml"
+        with request_vcr.use_cassette(cassette_name):
+            llm.messages.create(
+                model="claude-3-opus-20240229",
+                max_tokens=15,
+                messages=[{"role": "user", "content": "What does Nietzsche mean by 'God is dead'?"}],
+                metadata={"user_id": "1234567890"},
+            )
+
+    span = mock_tracer.pop_traces()[0][0]
+    assert span.get_tag("anthropic.request.user_id") == "1234567890"
+
+
 @pytest.mark.snapshot(token="tests.contrib.anthropic.test_anthropic.test_anthropic_llm", ignores=["resource"])
 def test_anthropic_llm_sync_create(anthropic, request_vcr):
     llm = anthropic.Anthropic()