Network intrusion detection is an invaluable part of an information security system. The rapid increase in the number of different types of attacks has increased the complexity involved in designing an intrusion detection system. Different techniques from various disciplines have been utilized to develop efficient IDS. Artificial Intelligence based techniques have a major role in the development of IDS, it has several benefits over other techniques. In this paper, several AI based techniques used for the development of IDS have been reviewed. Related studies have been compared by key concept used, advantages and disadvantages of each system and the data set used.