diff --git a/src/backend/core/api/viewsets.py b/src/backend/core/api/viewsets.py
index 0ee3c4269..d62181ae2 100644
--- a/src/backend/core/api/viewsets.py
+++ b/src/backend/core/api/viewsets.py
@@ -2602,6 +2602,8 @@ class DocumentViewSet(
             )
             raise
 
+        posthog_capture(PosthogEventName.DOC_LEFT, request.user, {}, document=document)
+
         return drf.response.Response(status=drf.status.HTTP_204_NO_CONTENT)
 
 
diff --git a/src/backend/core/tests/documents/test_api_documents_leave.py b/src/backend/core/tests/documents/test_api_documents_leave.py
index 82c0eded4..4f9144bd5 100644
--- a/src/backend/core/tests/documents/test_api_documents_leave.py
+++ b/src/backend/core/tests/documents/test_api_documents_leave.py
@@ -1,10 +1,13 @@
 """Test for the leave document API"""
 
+from unittest import mock
+
 import pytest
 from rest_framework import status
 from rest_framework.test import APIClient
 
 from core import factories, models
+from core.utils.analytics import PosthogEventName
 
 pytestmark = pytest.mark.django_db
 
@@ -83,10 +86,19 @@ def test_api_documents_leave_connected_user_with_link_trace(link_reach):
 
     client = APIClient()
     client.force_login(user)
-    response = client.post(f"/api/v1.0/documents/{document.id!s}/leave/")
+    with mock.patch("core.api.viewsets.posthog_capture") as mock_capture:
+        response = client.post(f"/api/v1.0/documents/{document.id!s}/leave/")
 
     assert response.status_code == status.HTTP_204_NO_CONTENT
 
+    # Leaving the document should be tracked in PostHog
+    mock_capture.assert_called_once_with(
+        PosthogEventName.DOC_LEFT,
+        user,
+        {},
+        document=document,
+    )
+
     assert not models.LinkTrace.objects.filter(document=document, user=user).exists()
     assert models.LinkTrace.objects.count() == 3
     assert models.DocumentAccess.objects.count() == 4
@@ -116,10 +128,19 @@ def test_api_documents_leave_connected_user_with_access(role, link_reach):
 
     client = APIClient()
     client.force_login(user)
-    response = client.post(f"/api/v1.0/documents/{document.id!s}/leave/")
+    with mock.patch("core.api.viewsets.posthog_capture") as mock_capture:
+        response = client.post(f"/api/v1.0/documents/{document.id!s}/leave/")
 
     assert response.status_code == status.HTTP_204_NO_CONTENT
 
+    # Leaving the document should be tracked in PostHog
+    mock_capture.assert_called_once_with(
+        PosthogEventName.DOC_LEFT,
+        user,
+        {},
+        document=document,
+    )
+
     assert not models.DocumentAccess.objects.filter(
         document=document, user=user
     ).exists()
@@ -189,10 +210,19 @@ def test_api_documents_leave_connected_user_with_access_and_link_trace(
 
     client = APIClient()
     client.force_login(user)
-    response = client.post(f"/api/v1.0/documents/{document.id!s}/leave/")
+    with mock.patch("core.api.viewsets.posthog_capture") as mock_capture:
+        response = client.post(f"/api/v1.0/documents/{document.id!s}/leave/")
 
     assert response.status_code == status.HTTP_204_NO_CONTENT
 
+    # Leaving the document should be tracked in PostHog
+    mock_capture.assert_called_once_with(
+        PosthogEventName.DOC_LEFT,
+        user,
+        {},
+        document=document,
+    )
+
     assert not models.DocumentAccess.objects.filter(
         document=document, user=user
     ).exists()
@@ -231,10 +261,19 @@ def test_api_documents_leave_connected_accessing_multiple_documents_leave_only_o
 
     client = APIClient()
     client.force_login(user)
-    response = client.post(f"/api/v1.0/documents/{document.id!s}/leave/")
+    with mock.patch("core.api.viewsets.posthog_capture") as mock_capture:
+        response = client.post(f"/api/v1.0/documents/{document.id!s}/leave/")
 
     assert response.status_code == status.HTTP_204_NO_CONTENT
 
+    # Leaving the document should be tracked in PostHog
+    mock_capture.assert_called_once_with(
+        PosthogEventName.DOC_LEFT,
+        user,
+        {},
+        document=document,
+    )
+
     assert not models.DocumentAccess.objects.filter(
         document=document, user=user
     ).exists()
@@ -281,10 +320,19 @@ def test_api_documents_leave_connected_leave_also_sub_documents(role, link_reach
 
     client = APIClient()
     client.force_login(user)
-    response = client.post(f"/api/v1.0/documents/{document.id!s}/leave/")
+    with mock.patch("core.api.viewsets.posthog_capture") as mock_capture:
+        response = client.post(f"/api/v1.0/documents/{document.id!s}/leave/")
 
     assert response.status_code == status.HTTP_204_NO_CONTENT
 
+    # Leaving the document should be tracked in PostHog
+    mock_capture.assert_called_once_with(
+        PosthogEventName.DOC_LEFT,
+        user,
+        {},
+        document=document,
+    )
+
     assert not models.DocumentAccess.objects.filter(
         document=document, user=user
     ).exists()
diff --git a/src/backend/core/utils/analytics.py b/src/backend/core/utils/analytics.py
index b65460eb3..b4b6c2d54 100644
--- a/src/backend/core/utils/analytics.py
+++ b/src/backend/core/utils/analytics.py
@@ -22,6 +22,7 @@ class PosthogEventName(StrEnum):
     DOC_FAVORITED = "doc_favorited"
     DOC_AI_ACTION = "doc_ai_action"
     DOC_MOVED = "doc_moved"
+    DOC_LEFT = "doc_left"
 
     # DocumentAccess
     DOC_ACCESS_CREATED = "doc_access_created"