Desmopressin (1-deamino-8-D-argininevasopressin, DDAVP) is a synthetic analog of the antidiuretic hormone L-argininevasopressin. DDAVP has been shown to increase the plasma concentration of endothelial factor VIII, thus increasing coagulant activity. There is evidence from controlled clinical trials indicating that DDAVP can reduce blood loss and transfusion requirements for individuals with normal coagulation profiles undergoing various surgical procedures. This study was conducted to evaluate the efficacy of the DDAVP in reduction of blood loss during orthognathic surgery. Twenty patients, 15 females and 5 males, undergoing bimaxillary osteotomy were randomized into two groups of ten. Perioperatively, group 1 patients received 20 micrograms of DDAVP infused over one-half hour. Group II patients did not receive DDAVP. Hypotensive anesthesia (mean arterial pressure < 60 mm Hg) was routinely employed for both groups. On average, the blood loss in group I patients was 144 ml less per patient than group II patients (p < 0.50). Only 2 of 10 patients in group I lost in excess of 750 ml, while 6 to 10 group II patients experienced blood loss greater than 750 ml (p < 0.20). The average postoperative hematocrit for patients in group I dropped by 6.17 of the preoperative mean hematocrit (p < 0.001). The average drop in hematocrits among the group II patients was 11.61 (p < 0.001). When collated, this hematocrit drop of 11.61 for group II and 6.17 for group I (recipients of DDAVP) proved to be significantly different (p < 0.01). It is concluded from this study that patients receiving a standard dose of DDAVP prior to bimaxillary osteotomy would experience reduced intraoperative blood loss, providing that blood pressure is well controlled and fluid replacement is carefully managed. No significant adverse side effects of desmopressin acetate were observed.