Upper gastrointestinal bleeding resulting from peptic ulcer disease is a potentially life-threatening situation. There are several reports on the association of ulcer disease and corticosteroid treatment, especially when high doses (greater than 40 mg/day) are used. Some categories of patients are prone to ulcer disease under steroid treatment. Prophylaxis in this situation therefore seems reasonable. We compared 23 consecutive liver transplant patients who received ranitidine prophylaxis with 33 previously transplanted patients who had no prophylaxis. In the control group there were 13 patients who had an ulcer, seven of whom bled. In the treated group two ulcers without upper GI bleeding were found. The results indicate that ranitidine can effectively reduce peptic ulcer disease in liver transplantation patients, despite the use of very high doses of corticosteroids.