A computer program has been developed to assist the physician in managing patients with hypercalcemia. The program requests appropriate information, such as the patient's serum calcium concentration, age and x-ray results. Based on the abnormalities detected, the program asks additional questions needed to suggest the most helpful course of action for evaluating or treating the patient's hypercalcemia. As soon as the data have been entered, the program generates an evaluation note that includes diagnostic possibilities, suggestions for additional laboratory studies, therapeutic recommendations and references to the medical literature. The program can be used from any general purpose teletype-compatible terminal (including cathode ray tube displays) connected to the Bell Telephone System. The time required to enter the data and obtain the evaluation note is approximately 4 minutes with a teletypewriter, and less if a faster terminal is used. The cost for computer time is comparable to that of a laboratory test. Comparison of diagnoses produced by the program with those obtained from pathologic examination of from consulting endocrinolgists shows that the program is sufficiently accurate for clinical use. Finnally, the explanation of the pathophysiology contained in the evaluation note may be useful to the student.