In 2011, ASCO updated its guideline for the use of antiemetics in oncology, informed by a systematic review of the medical literature. This is an abbreviated version of that guideline, which is available in full at www.asco.org/guidelines/antiemetics. Key changes from the prior update in 2006 include the following: Combined anthracycline and cyclophosphamide regimens were reclassified as highly emetic. Patients who receive this combination or any highly emetic agents should receive a 5-HT3 receptor antagonist, dexamethasone, and an NK1 receptor antagonist. A large trial validated the equivalency of fosaprepitant, a single-day intravenous formulation, with aprepitant; either therapy is appropriate. Preferential use of palonosetron is recommended for moderate emetic risk regimens, combined with dexamethasone. For low-risk agents, patients can be offered dexamethasone before the first dose of chemotherapy. Patients undergoing high emetic risk radiation therapy should receive a 5-HT3 receptor antagonist before each fraction and for 24 hours following treatment and may receive a 5-day course of dexamethasone during fractions 1 to 5. Continued symptom monitoring throughout therapy is recommended. Clinicians often underestimate the incidence of nausea, which is not as well controlled as vomiting. Detailed information about the development of the guideline as well as practice tools are available at www.asco.org/guidelines/antiemetics.