diff --git a/slack_sdk/web/async_base_client.py b/slack_sdk/web/async_base_client.py
index 65f852b69..2418b08c3 100644
--- a/slack_sdk/web/async_base_client.py
+++ b/slack_sdk/web/async_base_client.py
@@ -46,8 +46,6 @@ def __init__(
     ):
         self.token = None if token is None else token.strip()
         """A string specifying an `xoxp-*` or `xoxb-*` token."""
-        if not base_url.endswith("/"):
-            base_url += "/"
         self.base_url = base_url
         """A string representing the Slack API base URL.
         Default is `'https://slack.com/api/'`."""
diff --git a/slack_sdk/web/base_client.py b/slack_sdk/web/base_client.py
index 4ce67b0c3..e112d35c8 100644
--- a/slack_sdk/web/base_client.py
+++ b/slack_sdk/web/base_client.py
@@ -59,8 +59,6 @@ def __init__(
     ):
         self.token = None if token is None else token.strip()
         """A string specifying an `xoxp-*` or `xoxb-*` token."""
-        if not base_url.endswith("/"):
-            base_url += "/"
         self.base_url = base_url
         """A string representing the Slack API base URL.
         Default is `'https://slack.com/api/'`."""
diff --git a/slack_sdk/web/legacy_base_client.py b/slack_sdk/web/legacy_base_client.py
index 44d499709..c58e062a1 100644
--- a/slack_sdk/web/legacy_base_client.py
+++ b/slack_sdk/web/legacy_base_client.py
@@ -62,8 +62,6 @@ def __init__(
     ):
         self.token = None if token is None else token.strip()
         """A string specifying an `xoxp-*` or `xoxb-*` token."""
-        if not base_url.endswith("/"):
-            base_url += "/"
         self.base_url = base_url
         """A string representing the Slack API base URL.
         Default is `'https://slack.com/api/'`."""
diff --git a/tests/slack_sdk/web/test_web_client.py b/tests/slack_sdk/web/test_web_client.py
index e6c6697c4..024915a20 100644
--- a/tests/slack_sdk/web/test_web_client.py
+++ b/tests/slack_sdk/web/test_web_client.py
@@ -229,11 +229,3 @@ def test_user_auth_blocks(self):
             user_auth_blocks=[DividerBlock(), DividerBlock()],
         )
         self.assertIsNone(new_message.get("error"))
-
-    def test_base_url_appends_trailing_slash_issue_15141(self):
-        client = self.client
-        self.assertEqual(client.base_url, "http://localhost:8888/")
-
-    def test_base_url_preserves_trailing_slash_issue_15141(self):
-        client = WebClient(base_url="http://localhost:8888/")
-        self.assertEqual(client.base_url, "http://localhost:8888/")