The cost efficacy of various ondansetron regimens for the control of emesis induced by noncisplatin, moderately emetogenic chemotherapy was examined from a hospital perspective. Previous cost-efficacy analyses of ondansetron provide limited insight into the economic impact of ondansetron when used with moderately emetogenic chemotherapies. Clinical efficacy results of trials that used ondansetron to control emesis were retrieved from the biomedical literature published between January 1966 and December 2000. Only direct antiemetic treatment costs were considered. A total of 55 trials were analyzed, with a total of 22 regimens identified. Costs of antiemetic treatments were calculated by multiplying the milligrams of each product by the cost per milligram. For each injectable dose, the average cost of an administration device was Can$1.28. Pharmacy time required for preparing an i.v. dose was 2.5 minutes, at an average hourly rate of Can$25. Nursing time to administer each i.v. dose was estimated at one minute at an average rate of Can$23 per hour. The efficacy rate of the 22 regimens varied between 24.2% and 90.4%, while the cost varied from Can$20 to Can$413. A cost-efficacy analysis of ondansetron regimens for control of emesis caused by noncisplatin, moderately emetic antineoplastic treatment revealed regimens that should be avoided as well as regimens that are, in comparison, at least as efficacious and less expensive. The analysis supported the concomitant use of a corticosteroid, twice-daily administration of ondansetron, and limitation of ondansetron administration to a period not exceeding four days.