Privacy is very important in data mining. Association rule mining, is an important technique, has already been applied in a wide range of areas. Large databases cannot be secured by encryption or other techniques because of complexities. These security issues can be divided into two categories: data hiding and knowledge hiding. This paper deals with the problem of association rule mining which preserves the confidentiality of each database i.e. knowledge hiding. Knowledge hiding is concerned with the sanitization of confidential knowledge from the data.