The use of digital computers in the selection of good diagnostic and treatment strategies has received an increased attention in recent years. Major reason for this interest is the general desire to improve the ability of the clinician to deal with the difficult problems that can arise in the management of a patient. In this thesis, a computer-assisted consultation system for diagnosing diseases of thyroid gland has been built. Prior to development of the system, an algorithm has been developed for selecting the optimal test flow which can be used to help physicians to determine the best combination and sequence of tests for a particular diagnostic problem. This algorithm uses entropy concepts in the information theory and considers the relation between tests, patient``s status, and the patient``s available cost, time, and risk for tests, as well as physicians experiences.