diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1f252e8290..dbaa0c6a4f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,6 +11,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+### Added
+
+- `opentelemetry-instrumentation-requests` Detect synthetic sources on requests.
+  ([#3674](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/3674))
+
 ## Version 1.36.0/0.57b0 (2025-07-29)
 
 ### Fixed
diff --git a/instrumentation/opentelemetry-instrumentation-requests/src/opentelemetry/instrumentation/requests/__init__.py b/instrumentation/opentelemetry-instrumentation-requests/src/opentelemetry/instrumentation/requests/__init__.py
index 7cfc3a4fee..e3dfb84039 100644
--- a/instrumentation/opentelemetry-instrumentation-requests/src/opentelemetry/instrumentation/requests/__init__.py
+++ b/instrumentation/opentelemetry-instrumentation-requests/src/opentelemetry/instrumentation/requests/__init__.py
@@ -124,7 +124,16 @@ def response_hook(span, request_obj, response):
     _StabilityMode,
 )
 from opentelemetry.instrumentation.instrumentor import BaseInstrumentor
+from opentelemetry.instrumentation.requests.constants import (
+    BOT_PATTERNS,
+    TEST_PATTERNS,
+)
 from opentelemetry.instrumentation.requests.package import _instruments
+from opentelemetry.instrumentation.requests.semconv import (
+    ATTR_USER_AGENT_SYNTHETIC_TYPE,
+    USER_AGENT_SYNTHETIC_TYPE_VALUE_BOT,
+    USER_AGENT_SYNTHETIC_TYPE_VALUE_TEST,
+)
 from opentelemetry.instrumentation.requests.version import __version__
 from opentelemetry.instrumentation.utils import (
     is_http_instrumentation_enabled,
@@ -158,6 +167,33 @@ def response_hook(span, request_obj, response):
 _ResponseHookT = Optional[Callable[[Span, PreparedRequest, Response], None]]
 
 
+def _detect_synthetic_user_agent(user_agent: str) -> Optional[str]:
+    """
+    Detect synthetic user agent type based on user agent string contents.
+
+    Args:
+        user_agent: The user agent string to analyze
+
+    Returns:
+        USER_AGENT_SYNTHETIC_TYPE_VALUE_TEST if user agent contains any pattern from TEST_PATTERNS
+        USER_AGENT_SYNTHETIC_TYPE_VALUE_BOT if user agent contains any pattern from BOT_PATTERNS
+        None otherwise
+
+    Note: Test patterns take priority over bot patterns.
+    """
+    if not user_agent:
+        return None
+
+    user_agent_lower = user_agent.lower()
+
+    if any(test_pattern in user_agent_lower for test_pattern in TEST_PATTERNS):
+        return USER_AGENT_SYNTHETIC_TYPE_VALUE_TEST
+    if any(bot_pattern in user_agent_lower for bot_pattern in BOT_PATTERNS):
+        return USER_AGENT_SYNTHETIC_TYPE_VALUE_BOT
+
+    return None
+
+
 def _set_http_status_code_attribute(
     span,
     status_code,
@@ -234,6 +270,9 @@ def get_or_create_headers():
 
         url = redact_url(request.url)
 
+        # Get headers early for user agent detection
+        headers = get_or_create_headers()
+
         span_attributes = {}
         _set_http_method(
             span_attributes,
@@ -243,6 +282,12 @@ def get_or_create_headers():
         )
         _set_http_url(span_attributes, url, sem_conv_opt_in_mode)
 
+        # Check for synthetic user agent type
+        user_agent = headers.get("User-Agent")
+        synthetic_type = _detect_synthetic_user_agent(user_agent)
+        if synthetic_type:
+            span_attributes[ATTR_USER_AGENT_SYNTHETIC_TYPE] = synthetic_type
+
         metric_labels = {}
         _set_http_method(
             metric_labels,
@@ -297,7 +342,6 @@ def get_or_create_headers():
             if callable(request_hook):
                 request_hook(span, request)
 
-            headers = get_or_create_headers()
             inject(headers)
 
             with suppress_http_instrumentation():
diff --git a/instrumentation/opentelemetry-instrumentation-requests/src/opentelemetry/instrumentation/requests/constants.py b/instrumentation/opentelemetry-instrumentation-requests/src/opentelemetry/instrumentation/requests/constants.py
new file mode 100644
index 0000000000..cb6d6741df
--- /dev/null
+++ b/instrumentation/opentelemetry-instrumentation-requests/src/opentelemetry/instrumentation/requests/constants.py
@@ -0,0 +1,34 @@
+# Copyright The OpenTelemetry Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""
+Constants for OpenTelemetry requests instrumentation.
+
+This module contains configuration constants and pattern definitions used
+by the requests instrumentation for various features like synthetic user
+agent detection.
+"""
+
+# Test patterns to detect in user agent strings (case-insensitive)
+# These patterns indicate synthetic test traffic
+TEST_PATTERNS = [
+    "alwayson",
+]
+
+# Bot patterns to detect in user agent strings (case-insensitive)
+# These patterns indicate automated bot traffic
+BOT_PATTERNS = [
+    "googlebot",
+    "bingbot",
+]
diff --git a/instrumentation/opentelemetry-instrumentation-requests/src/opentelemetry/instrumentation/requests/semconv.py b/instrumentation/opentelemetry-instrumentation-requests/src/opentelemetry/instrumentation/requests/semconv.py
new file mode 100644
index 0000000000..7a0e3f48b1
--- /dev/null
+++ b/instrumentation/opentelemetry-instrumentation-requests/src/opentelemetry/instrumentation/requests/semconv.py
@@ -0,0 +1,47 @@
+# Copyright The OpenTelemetry Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""
+Semantic conventions for user agent synthetic type detection.
+
+This module defines constants for user agent synthetic type attributes and values
+according to OpenTelemetry semantic conventions.
+
+**EXPERIMENTAL**: This module contains experimental semantic conventions that are not
+yet part of the official OpenTelemetry semantic conventions specification. These
+attributes and values may experience breaking changes in future versions as the
+specification evolves.
+
+The semantic conventions defined here are used to classify synthetic traffic based
+on User-Agent header analysis, helping distinguish between:
+- Bot traffic (web crawlers, search engine bots)
+- Test traffic (monitoring systems, health checks)
+- Regular user traffic
+
+These experimental conventions may be:
+1. Modified with different attribute names or values
+2. Moved to official semantic convention packages
+3. Deprecated in favor of standardized alternatives
+4. Changed based on community feedback and specification updates
+
+Users should be prepared for potential breaking changes when upgrading and should
+monitor OpenTelemetry specification updates for official semantic convention releases.
+"""
+
+# User agent synthetic type attribute
+ATTR_USER_AGENT_SYNTHETIC_TYPE = "user_agent.synthetic.type"
+
+# User agent synthetic type values
+USER_AGENT_SYNTHETIC_TYPE_VALUE_BOT = "bot"
+USER_AGENT_SYNTHETIC_TYPE_VALUE_TEST = "test"
diff --git a/instrumentation/opentelemetry-instrumentation-requests/tests/test_user_agent_synthetic.py b/instrumentation/opentelemetry-instrumentation-requests/tests/test_user_agent_synthetic.py
new file mode 100644
index 0000000000..26cf5c68aa
--- /dev/null
+++ b/instrumentation/opentelemetry-instrumentation-requests/tests/test_user_agent_synthetic.py
@@ -0,0 +1,168 @@
+# Copyright The OpenTelemetry Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import httpretty
+import requests
+
+from opentelemetry.instrumentation.requests import RequestsInstrumentor
+from opentelemetry.instrumentation.requests.semconv import (
+    ATTR_USER_AGENT_SYNTHETIC_TYPE,
+    USER_AGENT_SYNTHETIC_TYPE_VALUE_BOT,
+    USER_AGENT_SYNTHETIC_TYPE_VALUE_TEST,
+)
+from opentelemetry.test.test_base import TestBase
+
+
+class TestUserAgentSynthetic(TestBase):
+    URL = "http://mock/status/200"
+
+    def setUp(self):
+        super().setUp()
+        RequestsInstrumentor().instrument()
+        httpretty.enable()
+        httpretty.register_uri(httpretty.GET, self.URL, body="Hello!")
+
+    def tearDown(self):
+        super().tearDown()
+        RequestsInstrumentor().uninstrument()
+        httpretty.disable()
+
+    def assert_span(self, num_spans=1):
+        span_list = self.memory_exporter.get_finished_spans()
+        self.assertEqual(num_spans, len(span_list))
+        if num_spans == 0:
+            return None
+        if num_spans == 1:
+            return span_list[0]
+        return span_list
+
+    def test_user_agent_bot_googlebot(self):
+        """Test that googlebot user agent is marked as 'bot'"""
+        headers = {
+            "User-Agent": "Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)"
+        }
+        requests.get(self.URL, headers=headers, timeout=5)
+
+        span = self.assert_span()
+        self.assertEqual(
+            span.attributes.get(ATTR_USER_AGENT_SYNTHETIC_TYPE),
+            USER_AGENT_SYNTHETIC_TYPE_VALUE_BOT,
+        )
+
+    def test_user_agent_bot_bingbot(self):
+        """Test that bingbot user agent is marked as 'bot'"""
+        headers = {
+            "User-Agent": "Mozilla/5.0 (compatible; bingbot/2.0; +http://www.bing.com/bingbot.htm)"
+        }
+        requests.get(self.URL, headers=headers, timeout=5)
+
+        span = self.assert_span()
+        self.assertEqual(
+            span.attributes.get(ATTR_USER_AGENT_SYNTHETIC_TYPE),
+            USER_AGENT_SYNTHETIC_TYPE_VALUE_BOT,
+        )
+
+    def test_user_agent_test_alwayson(self):
+        """Test that alwayson user agent is marked as 'test'"""
+        headers = {"User-Agent": "AlwaysOn-Monitor/1.0"}
+        requests.get(self.URL, headers=headers, timeout=5)
+
+        span = self.assert_span()
+        self.assertEqual(
+            span.attributes.get(ATTR_USER_AGENT_SYNTHETIC_TYPE),
+            USER_AGENT_SYNTHETIC_TYPE_VALUE_TEST,
+        )
+
+    def test_user_agent_case_insensitive(self):
+        """Test that detection is case insensitive"""
+        headers = {"User-Agent": "GOOGLEBOT/2.1"}
+        requests.get(self.URL, headers=headers, timeout=5)
+
+        span = self.assert_span()
+        self.assertEqual(
+            span.attributes.get(ATTR_USER_AGENT_SYNTHETIC_TYPE),
+            USER_AGENT_SYNTHETIC_TYPE_VALUE_BOT,
+        )
+
+        self.memory_exporter.clear()
+
+        headers = {"User-Agent": "ALWAYSON-Monitor/1.0"}
+        requests.get(self.URL, headers=headers, timeout=5)
+
+        span = self.assert_span()
+        self.assertEqual(
+            span.attributes.get(ATTR_USER_AGENT_SYNTHETIC_TYPE),
+            USER_AGENT_SYNTHETIC_TYPE_VALUE_TEST,
+        )
+
+    def test_user_agent_normal_browser(self):
+        """Test that normal browser user agents don't get synthetic type"""
+        headers = {
+            "User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36"
+        }
+        requests.get(self.URL, headers=headers, timeout=5)
+
+        span = self.assert_span()
+        self.assertNotIn(ATTR_USER_AGENT_SYNTHETIC_TYPE, span.attributes)
+
+    def test_no_user_agent_header(self):
+        """Test that requests without user agent don't get synthetic type"""
+        requests.get(self.URL, timeout=5)
+
+        span = self.assert_span()
+        self.assertNotIn(ATTR_USER_AGENT_SYNTHETIC_TYPE, span.attributes)
+
+    def test_empty_user_agent_header(self):
+        """Test that empty user agent doesn't get synthetic type"""
+        headers = {"User-Agent": ""}
+        requests.get(self.URL, headers=headers, timeout=5)
+
+        span = self.assert_span()
+        self.assertNotIn(ATTR_USER_AGENT_SYNTHETIC_TYPE, span.attributes)
+
+    def test_user_agent_substring_match(self):
+        """Test that substrings are detected correctly"""
+        # Test googlebot in middle of string
+        headers = {"User-Agent": "MyApp/1.0 googlebot crawler"}
+        requests.get(self.URL, headers=headers, timeout=5)
+
+        span = self.assert_span()
+        self.assertEqual(
+            span.attributes.get(ATTR_USER_AGENT_SYNTHETIC_TYPE),
+            USER_AGENT_SYNTHETIC_TYPE_VALUE_BOT,
+        )
+
+        self.memory_exporter.clear()
+
+        # Test alwayson in middle of string
+        headers = {"User-Agent": "TestFramework/1.0 alwayson monitoring"}
+        requests.get(self.URL, headers=headers, timeout=5)
+
+        span = self.assert_span()
+        self.assertEqual(
+            span.attributes.get(ATTR_USER_AGENT_SYNTHETIC_TYPE),
+            USER_AGENT_SYNTHETIC_TYPE_VALUE_TEST,
+        )
+
+    def test_user_agent_priority_alwayson_over_bot(self):
+        """Test that alwayson takes priority if both patterns match"""
+        headers = {"User-Agent": "alwayson-googlebot/1.0"}
+        requests.get(self.URL, headers=headers, timeout=5)
+
+        span = self.assert_span()
+        # alwayson should be checked first and return 'test'
+        self.assertEqual(
+            span.attributes.get(ATTR_USER_AGENT_SYNTHETIC_TYPE),
+            USER_AGENT_SYNTHETIC_TYPE_VALUE_TEST,
+        )