The efficacy of ultra-low-dose-aprotinin (ULDA) in 'high-risk' two valve replacement surgery, was evaluated in this prospective, randomized, double-blind study. Forty adult high-risk patients undergoing elective two valve replacement surgery, were included. The patients were divided into 2 groups of 20 each. In Group I, aprotinin in a dose of 1,000,000 KIU was administered from the end of anaesthesia induction to the time of sternotomy after a 1 ml of test dose. In Group II (control), 100 ml of normal saline was administered in a similar fashion. Coagulation parameters, blood loss, and amount of transfusion of blood / blood products were measured at specific intervals. The postoperative chest tube drainage in the first 24 hours was significantly less 203+/-35 ml (p<0.05) in Group I as compared with 490+/-104 ml in group II and consequently, Group I patients received significantly less (p<0.05) red cell concentrates and platelet transfusion. There was a significant decrease in the length of postoperative elective ventilation, intensive care unit (ICU) stay and direct costs involved in the hospital expenses with the use of ULDA. We conclude that ULDA is safe and effective in 'high-risk' two-valve replacement surgery to reduce postoperative bleeding, postoperative length of intubation and ICU stay; use of ULDA is associated with significant direct cost savings.