Though antiemetic therapy has improved markedly in the past 15 years, patients still regard nausea and vomiting as two of the most distressing adverse events during chemotherapy. A major progress was the development of the serotonin3 (5-HT3) receptor antagonists. A possible antiemetic effect, achieved by interference with the "serotonergic system", is not restricted to antagonism at 5-HT3 receptors, however, but also includes agonism at 5-HT1A and 5-HT2 receptors, and serotonin synthesis inhibitors. The number of receptors thought to be involved in the emetic reflex has been augmented by neurokinin1 receptors with substance P as the preferred ligand. Animal studies have demonstrated a broad antiemetic profile of substance P antagonists. The somatostatin analogue octreotide has an antiemetic effect in patients with gastrointestinal obstruction, but has not been investigated against chemotherapy-induced emesis. The next few years will disclose, whether the efficacy and safety profiles of one or more of these drugs will make it clinically useful in the treatment of chemotherapy-induced nausea and vomiting.