1. O(logN) search time compared to hashing's O(1). However, a bad hashing function can do more bad ! 2. Naturally saving of order in BST while there is nothing in Hash 3. BST works for search operation like = and also == but hashing works only for == 4. BST height is a major problem, so I think traversing a long/deep tree that too recursively is bad for machines ... while there is nothing like that in hashing .... we do not use recursion to find stuff!!! 5. like 4 above .. maintainability is issue with BST to make search time O(logN) ..