diff --git a/trees/bst_pre_sucessor.py b/trees/bst_pre_sucessor.py
new file mode 100644
index 0000000..db3bcc7
--- /dev/null
+++ b/trees/bst_pre_sucessor.py
@@ -0,0 +1,23 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+# author: bt3gl
+
+
+def successor(root):
+  
+  root = root.right
+  
+  while root.left:
+      root = root.left
+      
+  return root
+
+
+def predecessor(root):
+  
+  root = root.left
+  
+  while root.right:
+      root = root.right
+  
+  return root