Purpose: To assess the cost-effectiveness of prophylactic therapy (I .25 mg droperidol or 50 mg dolasetron iv) ~s no prophylaxis (rescue therapy) for the prevention of post-operative nausea and vomiting (PONV) from a Canadian hospital perspective. Mcthods: Design: A predictive decision analytic model using previously published clinical and economic evaluations, and costs of medical care in Canada. SubJects: Ambulatory gynecology surgery patients. Interventions: Three strategies administered prior to emergence from anesthesia were compared: 1.25 mg droperidol iv, 50 mg dolasetron iv; and no prophylaxis (rescue therapy). Results: The base case mean cost per patient receiving dolasetron prophylaxis was $28.08 CAN compared with $26.88 CAN per patient receiving droperidol prophylaxis, resulting in a marginal cost of $I .20 CAN. This difference translated in an additional cost of $12.00 CAN for the dolasetron strategy per adverse event avoided over the droperidol strategy. The base case mean cost per patient not receiving prophylaxis was $26.92 resulting in marginal costs of $I. 16 CAN and $0.04 CAN when compared to dolasetron and droperidol, respectively. Compared with the no prophylaxis strategy, dolasetron prophylaxis resulted in an incremental cost-effectiveness ratio of $5.82 CAN per additional PONV-free patient. The mean costs incurred per PONV-free patient were calculated to be $48.41 for the dolasetron strategy, $46.34 for the droperidol strategy and $70.83 for the no prophylaxis strategy. Conclusions: Dolasetron and droperidol given intraoperatively were more cost-effective than no prophylaxis for PONY in patients undergoing ambulatory gynecologic surgery. The difference between the two agents was small and favoured droperidol. The model was robust to plausible changes through sensitivity analyses. Obj~ds I~valuer la rentabilit6 d'une thdrapie prophylactique (I,25 mg de drop&idol ou 50 mg de dolas6tron iv) vs aucune prophylaxie dans le but de pr6venir les naus6es et vomissements postop6ratoires (NVPO) dans le contexte d'un h6pital canadien. M&hodc : Devis de recherche : Un module analytique de d6cision prddictive bas6 sur les 6valuations cliniques et &onomiques d6j~ publides et sur le coot des soins m6dicaux au Canada. Sujets : Patientes de chirurgie gyn&ologique ambulatoire. Interventions : Trois prescriptions administrdes avant le rdveil ont dtd compardes; 1,25 mg de drop6ddol iv, 50 mg dolas&ron iv; et aucune prophylaxie. 3~.,~fllmts : Le coOt moyen de base par patient qui a regu du dolas&ron a dr6 de 28,08 $ CAN compar6 ~ 26,88 $ par patient qui a regu du drop&idol, une diff6rence de 1,20 $. Cette diff6rence s'est traduite en un coot additionnel de I ZOO $ CAN, avec la th6rapie au dolas&ron compar6e ~ la th6rapie au drop&idol, pour chaque 6v6nement ddfavorable 6vitd. Le coOt de base moyen par patient sans prophylaxie 6tait de 26,92 $ dtablissant une diff6rence de I, t 6 $et 0,04 $ compar6 au dolas&ron et au drop&idol, respectivement. Compar~e ~ la stratdgie de non-prophylaxie, la prophylaxie au dolasdtron...