OBJECTIVE The incidence and duration of chemotherapy-induced emesis, pathophysiology of the emetic response, and antiemetic treatment of options are reviewed. BACKGROUND Nausea and vomiting are among the most common and debilitating side effects of cancer chemotherapy. If not controlled, these side effects may interfere with the delivery of potentially life-saving treatment. Acute, delayed, and anticipatory nausea and vomiting may be prevented by appropriate antiemetic therapy. Drug selection is based on the emetogenicity of the patient's cancer treatment and potency of the antiemetic agent. Efficacy and safety of the antiemetic regimen are often improved by combining agents with different mechanisms of action. CONCLUSIONS By preventing and controlling chemotherapy-induced emesis, clinicians may improve cancer patients' functional status and quality of life significantly. Improved tolerability may lead to greater patient acceptance of chemotherapy and prevent premature withdrawal from or cessation of treatment. Controlling chemotherapy-induced emesis also helps to decrease the direct and indirect costs of managing cancer.