Bleeding after cardiopulmonary bypass remains a cause for concern, requiring reexploration of the chest in approximately 3 percent of patients who have had operations on the heart. We examined the possibility that this problem might be alleviated by desmopressin acetate [DDAVP], synthetic vasopressin analogue that lacks vasoconstrictor activity. In a prospective, randomized trial, we studied the effect of intraoperative desmopressin acetate in 20 patients [the treated group 10 patients and the control group 10 patients] undergoing various cardiac operations requiring cardiopulmonary bypass. The result showed that the early postoperative [during first 24hrs] and mean postoperative blood loss [first 3 days] of the treated group were significantly reduced than the control group[447ulcorner199ml in the treated group versus 746ulcorner199ml in the treated group versus 746ulcorner295 ml in the control group, p=0.014; meanulcornerstandard deviation and 675ulcorner276 ml in the treated group versus 1006ulcorner303 ml in control group, p=0.019]. The mean red-cell transfusion in first 3days were reduced in the treated group than the control group [3.3ulcorner1.7 units vs 4.9ulcorner1.7units, P=0.051]. There were no untoward side effects of desmopressin acetate. We conclude that the administration of desmopressin acetate can be recommended to reduce blood loss and blood conservation in patients undergoing cardiac operations.