The incidence and possible etiologic factors of acute pancreatitis and hyperamylasemia were statistically evaluated in renal transplant recipients. Two hundred twenty-four patients were randomized in a prospective trial of cyclosporine and antilymphoblast azathioprine immunosuppressive regimens. They had a median follow-up of 20 months. Pancreatitis developed in 8 patients and hyperamyl asemia developed in 20 patients. There were no statistical relationships between the incidences of pancreatitis and hyperamylasemia and the immunosuppressive drugs or viral infections. However, pancreatitis developed in 11 percent of the transplant patients with repeatedly elevated serum calcium levels (37 patients, p less than 0.01) and hyperamylasemia developed in 19 percent (p less than 0.025). Other etiologic factors, such as gallstones, alcoholism, and corticosteroids, played a minor role in this patient population. These results suggest that hypercalcemia is a major etiologic factor for pancreatitis in renal transplant recipients.