Artificial Intelligence has emerged as the most promising technique in the field of computational research and development. The challenges to the present computational needs are to develop such intelligent systems which can take advantage of the biological intelligence. There are a lot of techniques and algorithms available in order to accomplish these challenges. Some of the biologically inspired computational intelligence methods are neural network, genetic algorithm, fuzzy logic, swarm intelligence, cellular automata and artificial immune system etc. The application area of AIS covers computer security, fraud detection, pattern recognition, adaptive control, optimization and data mining. During the last few years AIS algorithms are being exercised in some data mining applications such as classification, clustering and association rule mining. This book is an introduction to the artificial immune system and its application in the field of data mining. It is a step towards the study of well-discussed AIS algorithms particularly the clonal selection mechanism in detail. The book uses traditional association rule mining algorithm in combination with clonal selection algorithm.