This paper uses an evidence-based approach whenever possible to formulate recommendations, emphasizing the results of controlled trials concerning the best use of antiemetic agents. We address issues of dose, schedule, and route of administration of five selective 5-HT(3) antagonists. We conclude that for each of these five drugs, there is a plateau in therapeutic efficacy above which further dose escalation does not improve outcome. Furthermore, for all classes of antiemetic agents, a single dose is as effective as multiple doses or a continuous infusion. The oral route is as efficacious as the intravenous route of administration, even with chemotherapy of high emetic risk. Selective antagonists of the type 3 serotonin receptor (5-HT(3)) in combination with dexamethasone and aprepitant are the standard of care for the prevention of emesis following chemotherapy of high emetic risk.