Important progress in the prophylaxis of chemotherapy-induced acute and delayed emesis has been achieved but some fundamental needs still remain that requires new, efficacious antiemetic drugs.A critical review of the results of published studies of aprepitant, a new NK1 receptor antagonist, and of palonosetron, a 5-HT3 receptor antagonist with a longer half-life.Aprepitant combined with dexamethasone and a 5-HT3 antagonist significantly increased the control of acute emesis with respect to dexamethasone and a 5-HT3 antagonist alone after cisplatin and moderately emetogenic chemotherapy. For cisplatin nausea, aprepitant combined with dexamethasone significantly increased the control of delayed emesis with respect to dexamethasone alone, while for moderately emetogenic chemotherapy aprepitant is superior to a 5-HT3 antagonist in the control of delayed emesis. Palonosetron showed superior or similar efficacy to ondansetron and dolasetron in patients submitted to moderately emetogenic chemotherapy and similar efficacy to ondansetron in patients submitted to cisplatin.More studies are necessary comparing aprepitant alone or combined with dexamethasone with respect to the recommended antiemetic drugs for the prevention of delayed emesis induced by cisplatin and moderately emetogenic chemotherapy as well as for palonosetron combined with dexamethasone with respect to other 5-HT3 antagonists combined with dexamethasone.