First-generation serotonin receptor antagonists greatly improved the control of chemotherapy-induced nausea and vomiting (CINV) during the 1990s. A new class of agents, neurokinin-1 receptor antagonists, was introduced in March 2003 and produced even greater control of CINV when used in combination with a serotonin receptor antagonist and a corticosteroid. In July 2003, palonosetron, a new second-generation serotonin receptor antagonist that has greater potency and a longer half-life than first-generation serotonin receptor antagonists, was introduced. This clinical update reviews studies that were conducted to evaluate these new agents.