The effect of the Kallikrein inhibitor, aprotinin, on hydrochlorothiazide and furosemide inducing pancreatitis has been studied in male rats. Treatment of animals with hydrochlorothiazide and furosemide for two weeks significantly increased serum lipase, amylase and glucose levels. The drugs therapy markedly reduced serum potassium level. Concurrent administration of aprotinin with hydrochlorothiazide and furosemide succeeded to ameliorate the elevated levels of serum lipase, amylase and glucose. Aprotinin failed to correct the hypokalemic effect of diuretics therapy. Histopathological studies revealed that aprotinin improved the picture of the pancreas and beta-cells which were partialy destroyed by hydrochlorothiazide and furosemide.