Nausea and vomiting are considered to be among the most distressing consequences of cytotoxic chemotherapies. Currently, there are several novel 5-HT3 receptor antagonists for the treatment of chemotherapy-induced nausea and vomiting (CINV), including ondansetron, granisetron, and dolasetron. These agents provide significant improvement in the management of acute emesis but are ineffective at preventing delayed emesis. In 2003, a new 5-HT 3 receptor antagonist, palonosetron HCL (Aloxi®), was introduced to the U.S. market. Palonosetron was found to be effective in preventing delayed CINV. Indeed, palonosetron was the first and only 5-HT3 receptor antagonist approved by the FDA for the prevention of both acute and delayed CINV. More recently, studies on the role of substance P in the emetic process led to the development of aprepitant (Emend®) for the prevention of delayed emesis in combination with 5-HT3 receptor antagonists. Despite these major advances, CINV remains uncontrolled in some patients. Current efforts are focused on treating refractory emesis and include both the clinical evaluation of compounds marketed for other indications and the preclinical evaluation of novel molecules targeting other transmitters in the emetic pathway. Ongoing work in pharmacogenomics has postulated several candidate genes that could be involved in emetic sensitivity and responsiveness to antiemetic therapy. Investigations into the pharmacogenomics of CINV may someday be able to aid in the identification of high risk patients and patients unlikely to respond to conventional therapies. Copyright © 2006 Jones and Bartlett Publishers, Inc.