This paper is a review of the recommendations for the prophylaxis of acute emesis induced by moderately emetogenic chemotherapy as concluded at the Perugia Consensus Conference, which took place at the end of March 2004. The review focuses on new studies appearing since the last consensus conference in 1997. The following issues are addressed: dose and schedule of antiemetics, different groups of antiemetics such as corticosteroids, serotonin (5-HT(3))-receptor antagonists, dopamine D(2) receptor antagonists, and neurokinin (NK(1)) receptor antagonists. Antiemetic prophylaxis in patients receiving multiple cycles of moderately emetogenic chemotherapy is also reviewed. Consensus statements are given, including optimal dose and schedule of 5-HT(3)-receptor antagonists and of dexamethasone. The new 5-HT(3)-receptor antagonist, palonosetron, is a reasonable alternative to the well-established agents of this class--ondansetron, granisetron, tropisetron and dolasetron. It is concluded that the best prophylaxis in patients receiving moderately emetogenic chemotherapy is still the combination of one of the 5-HT(3)-receptor antagonists and dexamethasone. The results of studies adding a NK(1)-receptor antagonist to this combination are awaited and might change future recommendations.