A 72-year-old woman had been given cimetidine 400mg/day for her gastritis since June 17, 1987. On August 8, she developed oral bleeding. Peripheral blood showed pancytopenia (WBC 1,900/microliters, RBC 208 x 10(4)/microliters, Plt 0.8 x 10(4)/microliters) and bone marrow studies revealed markedly depressed hematopoiesis. Bolus methylprednisolone and high dose gamma globulin were administered, but not effective. On December 11, 1987, she lapsed into coma and died three days later. Autopsy disclosed nonbacterial thrombotic endocarditis and cerebral infarction.