diff --git a/docs_src/security/tutorial006.py b/docs_src/security/tutorial006.py
index 29121ffd6..5b9e9a8e8 100644
--- a/docs_src/security/tutorial006.py
+++ b/docs_src/security/tutorial006.py
@@ -3,7 +3,7 @@ from fastapi.security import HTTPBasic, HTTPBasicCredentials
 
 app = FastAPI()
 
-security = HTTPBasic()
+security = HTTPBasic(realm="simple")
 
 
 @app.get("/users/me")
diff --git a/docs_src/security/tutorial006_an.py b/docs_src/security/tutorial006_an.py
index 985e4b2ad..43e970397 100644
--- a/docs_src/security/tutorial006_an.py
+++ b/docs_src/security/tutorial006_an.py
@@ -4,7 +4,7 @@ from typing_extensions import Annotated
 
 app = FastAPI()
 
-security = HTTPBasic()
+security = HTTPBasic(realm="simple")
 
 
 @app.get("/users/me")
diff --git a/docs_src/security/tutorial006_an_py39.py b/docs_src/security/tutorial006_an_py39.py
index 03c696a4b..721716a15 100644
--- a/docs_src/security/tutorial006_an_py39.py
+++ b/docs_src/security/tutorial006_an_py39.py
@@ -5,7 +5,7 @@ from fastapi.security import HTTPBasic, HTTPBasicCredentials
 
 app = FastAPI()
 
-security = HTTPBasic()
+security = HTTPBasic(realm="simple")
 
 
 @app.get("/users/me")
diff --git a/fastapi/security/http.py b/fastapi/security/http.py
index 0d1bbba3a..cc231fb38 100644
--- a/fastapi/security/http.py
+++ b/fastapi/security/http.py
@@ -154,13 +154,13 @@ class HTTPBasic(HTTPBase):
             ),
         ] = None,
         realm: Annotated[
-            Optional[str],
+            str,
             Doc(
                 """
                 HTTP Basic authentication realm.
                 """
             ),
-        ] = None,
+        ],
         description: Annotated[
             Optional[str],
             Doc(
diff --git a/tests/test_security_http_basic_empty_realm.py b/tests/test_security_http_basic_empty_realm.py
new file mode 100644
index 000000000..eb5513f30
--- /dev/null
+++ b/tests/test_security_http_basic_empty_realm.py
@@ -0,0 +1,30 @@
+from fastapi import Depends, FastAPI
+from fastapi.security import HTTPBasic, HTTPBasicCredentials
+from fastapi.testclient import TestClient
+
+app = FastAPI()
+
+security = HTTPBasic(realm="")
+
+
+@app.get("/users/me")
+def read_current_user(credentials: HTTPBasicCredentials = Depends(security)):
+    return {"username": credentials.username, "password": credentials.password}
+
+
+client = TestClient(app)
+
+
+def test_security_http_basic_empty_realm():
+    response = client.get("/users/me", auth=("john", "secret"))
+    assert response.status_code == 200, response.text
+    assert response.json() == {"username": "john", "password": "secret"}
+
+
+def test_security_http_basic_invalid_credentials_empty_realm():
+    response = client.get(
+        "/users/me", headers={"Authorization": "Basic notabase64token"}
+    )
+    assert response.status_code == 401, response.text
+    assert response.headers["WWW-Authenticate"] == "Basic"
+    assert response.json() == {"detail": "Invalid authentication credentials"}
diff --git a/tests/test_security_http_basic_optional.py b/tests/test_security_http_basic_optional.py
index 7071f381a..ab674a99b 100644
--- a/tests/test_security_http_basic_optional.py
+++ b/tests/test_security_http_basic_optional.py
@@ -7,7 +7,7 @@ from fastapi.testclient import TestClient
 
 app = FastAPI()
 
-security = HTTPBasic(auto_error=False)
+security = HTTPBasic(realm="simple", auto_error=False)
 
 
 @app.get("/users/me")
diff --git a/tests/test_tutorial/test_security/test_tutorial006.py b/tests/test_tutorial/test_security/test_tutorial006.py
index 9587159dc..ba10a929b 100644
--- a/tests/test_tutorial/test_security/test_tutorial006.py
+++ b/tests/test_tutorial/test_security/test_tutorial006.py
@@ -32,7 +32,7 @@ def test_security_http_basic_no_credentials(client: TestClient):
     response = client.get("/users/me")
     assert response.json() == {"detail": "Not authenticated"}
     assert response.status_code == 401, response.text
-    assert response.headers["WWW-Authenticate"] == "Basic"
+    assert response.headers["WWW-Authenticate"] == 'Basic realm="simple"'
 
 
 def test_security_http_basic_invalid_credentials(client: TestClient):