diff --git a/data_structures/binary tree/AVLtree.py b/data_structures/binary tree/AVLtree.py
new file mode 100644
index 000000000..cb27004b6
--- /dev/null
+++ b/data_structures/binary tree/AVLtree.py	
@@ -0,0 +1,255 @@
+# -*- coding: utf-8 -*-
+'''
+An auto-balanced binary tree!
+'''
+import math
+import random
+class my_queue:
+    def __init__(self):
+        self.data = []
+        self.head = 0
+        self.tail = 0
+    def isEmpty(self):
+        return self.head == self.tail
+    def push(self,data):
+        self.data.append(data)
+        self.tail = self.tail + 1
+    def pop(self):
+        ret = self.data[self.head]
+        self.head = self.head + 1
+        return ret
+    def count(self):
+        return self.tail - self.head
+    def print(self):
+        print(self.data)
+        print("**************")
+        print(self.data[self.head:self.tail])
+        
+class my_node:
+    def __init__(self,data):
+        self.data = data
+        self.left = None
+        self.right = None
+        self.height = 1
+    def getdata(self):
+        return self.data
+    def getleft(self):
+        return self.left
+    def getright(self):
+        return self.right
+    def getheight(self):
+        return self.height
+    def setdata(self,data):
+        self.data = data
+        return
+    def setleft(self,node):
+        self.left = node
+        return
+    def setright(self,node):
+        self.right = node
+        return
+    def setheight(self,height):
+        self.height = height
+        return
+
+def getheight(node):
+    if node is None:
+        return 0
+    return node.getheight()
+
+def my_max(a,b):
+    if a > b:
+        return a
+    return b
+
+
+
+def leftrotation(node):
+    '''
+            A                      B
+           / \                    / \
+          B   C                  Bl  A
+         / \       -->          /   / \
+        Bl  Br                 UB Br  C
+       /
+     UB
+  
+    UB = unbalanced node  
+    '''
+    print("left rotation node:",node.getdata())
+    ret = node.getleft()
+    node.setleft(ret.getright())
+    ret.setright(node)
+    h1 = my_max(getheight(node.getright()),getheight(node.getleft())) + 1
+    node.setheight(h1)
+    h2 = my_max(getheight(ret.getright()),getheight(ret.getleft())) + 1         
+    ret.setheight(h2)
+    return ret
+
+def rightrotation(node):
+    '''
+        a mirror symmetry rotation of the leftrotation
+    '''
+    print("right rotation node:",node.getdata())
+    ret = node.getright()
+    node.setright(ret.getleft())
+    ret.setleft(node)
+    h1 = my_max(getheight(node.getright()),getheight(node.getleft())) + 1
+    node.setheight(h1)
+    h2 = my_max(getheight(ret.getright()),getheight(ret.getleft())) + 1         
+    ret.setheight(h2)
+    return ret
+
+def rlrotation(node):
+    '''
+            A              A                    Br      
+           / \            / \                  /  \
+          B   C    RR    Br  C       LR       B    A
+         / \       -->  /  \         -->    /     / \
+        Bl  Br         B   UB              Bl    UB  C  
+             \        /
+             UB     Bl
+    RR = rightrotation   LR = leftrotation
+    '''
+    node.setleft(rightrotation(node.getleft()))
+    return leftrotation(node)
+
+def lrrotation(node):
+    node.setright(leftrotation(node.getright()))
+    return rightrotation(node)
+
+
+def insert_node(node,data):
+    if node is None:
+        return my_node(data)
+    if data < node.getdata():
+        node.setleft(insert_node(node.getleft(),data))
+        if getheight(node.getleft()) - getheight(node.getright()) == 2: #an unbalance detected
+            if data < node.getleft().getdata():       #new node is the left child of the left child
+                node = leftrotation(node)
+            else:
+                node = rlrotation(node)             #new node is the right child of the left child
+    else:
+        node.setright(insert_node(node.getright(),data))
+        if getheight(node.getright()) - getheight(node.getleft()) == 2:
+            if data < node.getright().getdata():
+                node = lrrotation(node)
+            else:
+                node = rightrotation(node)
+    h1 = my_max(getheight(node.getright()),getheight(node.getleft())) + 1
+    node.setheight(h1)
+    return node
+
+def getRightMost(root):
+    while root.getright() is not None:
+        root = root.getright()
+    return root.getdata()
+def getLeftMost(root):
+    while root.getleft() is not None:
+        root = root.getleft()
+    return root.getdata()
+
+def del_node(root,data):
+    if root.getdata() == data:
+        if root.getleft() is not None and root.getright() is not None:
+            temp_data = getLeftMost(root.getright())
+            root.setdata(temp_data)
+            root.setright(del_node(root.getright(),temp_data))
+        elif root.getleft() is not None:
+            root = root.getleft()
+        else:
+            root = root.getright()
+    elif root.getdata() > data:
+        if root.getleft() is None:
+            print("No such data")
+            return root
+        else:
+            root.setleft(del_node(root.getleft(),data))
+    elif root.getdata() < data:
+        if root.getright() is None:
+            return root
+        else:
+            root.setright(del_node(root.getright(),data))
+    if root is None:
+        return root
+    if getheight(root.getright()) - getheight(root.getleft()) == 2:
+        if getheight(root.getright().getright()) > getheight(root.getright().getleft()):
+            root = rightrotation(root)
+        else:
+            root = lrrotation(root)
+    elif getheight(root.getright()) - getheight(root.getleft()) == -2:
+        if getheight(root.getleft().getleft()) > getheight(root.getleft().getright()):
+            root = leftrotation(root)
+        else:
+            root = rlrotation(root)
+    height = my_max(getheight(root.getright()),getheight(root.getleft())) + 1
+    root.setheight(height)
+    return root
+
+class AVLtree:
+    def __init__(self):
+        self.root = None
+    def getheight(self):
+#        print("yyy")
+        return getheight(self.root)
+    def insert(self,data):
+        print("insert:"+str(data))
+        self.root = insert_node(self.root,data)
+        
+    def del_node(self,data):
+        print("delete:"+str(data))
+        if self.root is None:
+            print("Tree is empty!")
+            return
+        self.root = del_node(self.root,data)
+    def traversale(self): #a level traversale, gives a more intuitive look on the tree
+        q = my_queue()
+        q.push(self.root)
+        layer = self.getheight()
+        if layer == 0:
+            return
+        cnt = 0
+        while not q.isEmpty():
+            node = q.pop()
+            space = " "*int(math.pow(2,layer-1))
+            print(space,end = "")
+            if node is None:
+                print("*",end = "")
+                q.push(None)
+                q.push(None)
+            else:
+                print(node.getdata(),end = "")
+                q.push(node.getleft())
+                q.push(node.getright())
+            print(space,end = "")
+            cnt = cnt + 1
+            for i in range(100):
+                if cnt == math.pow(2,i) - 1:
+                    layer = layer -1 
+                    if layer == 0:
+                        print()
+                        print("*************************************")
+                        return
+                    print()
+                    break
+        print()
+        print("*************************************")
+        return
+    
+    def test(self):
+        getheight(None)
+        print("****")
+        self.getheight()
+if __name__ == "__main__":
+    t = AVLtree()
+    t.traversale()
+    l = list(range(10))
+    random.shuffle(l)
+    for i in l:
+        t.insert(i)
+        t.traversale()
+        
+    random.shuffle(l)
+    for i in l:
+        t.del_node(i)
+        t.traversale()