Physicians use differential diagnosis technique extensively for identifying specific diseases in patients. They identify certain parameters that are out of a specific range in medical reports of patients and on basis of these parameters; they refer patients to specialists. The Clinical Decision Support System can be used by medical students and general physicians to help them with diagnosis based upon Blood test results. It is to assist clinicians at the point of decision making while referring them to subject matter specialists. The Clinical Decision Support System takes input data from database, diagnoses and provides a list of possible diseases and to which specialist the patient should be referred to. The software has Patient Blood Test Data and List of Diseases database. Joining these different databases and a decision making mechanism based upon symptom patterns that are followed in different diseases. The Blood Test Results of patients will be available to the doctors on single click along with the all possible diagnosis and recommendation to concerned specialist.