Aprotinin is effective in promoting hemostasis, especially in cardiac surgery with extracorporeal circulation. Its efficacy has been shown, using a full dose, in coronary bypass graft operations. Few reports have been made about aprotinin use in valve operations. In the present study, the effects of low-dose aprotinin were analyzed in 18 patients undergoing valve reoperation. Postoperative blood loss (470 ml) was significantly less than in 18 control patients. No adverse effects were noted, except for one case of allergic reaction. Thus, systematic use of low-dose aprotinin should be considered in valve reoperation, except in cases of re-exposure to the drug, or allergic reaction.