Clinical Decision Support systems link health observations with health knowledge to determine health option by clinicians for improved health care. The main idea of Clinical Decision Support System is a set of rules derived from medical professionals applied on a dynamic knowledge. Data mining is well suited to give decision support for the healthcare. There are several classification techniques available that can be used for clinical decision support system. Different techniques are used for different diagnosis. In this paper, various classification techniques for clinical decision support system are discussed with example. .