In the past few years a combination of a 5-HT3 receptor antagonist plus dexamethasone has been shown to be the most efficacious antiemetic prophylaxis of acute emesis induced by cisplatin and moderately emetogenic chemotherapy. In the prevention of cisplatin-induced delayed emesis oral metoclopramide or ondansetron, both combined with dexamethasone, offer similar antiemetic protection. Due to its lower cost the metoclopramide regimen remains the treatment of choice, whereas the ondansetron one is a valid alternative treatment that may be preferred in patients who present acute emesis. In the prevention of delayed emesis induced by moderately emetogenic chemotherapy ondansetron and dexamethasone have been shown superior to placebo. On the other hand, a recent observational study suggested that patients presenting acute vomiting or acute moderate-severe nausea, having a high incidence of delayed emesis, should always receive antiemetic prophylaxis. Instead, patients obtaining complete protection from acute emesis may not require any antiemetic prophylaxis.