Goals of work: Prevention of chemotherapy-induced nausea and vomiting (CINV) with standard antiemetics has been more difficult to achieve in female patients. Data from two phase III trials of the NK1 antagonist aprepitant were assessed for potential effect of gender on treatment response. Patients and methods: 1,044 patients receiving cisplatin (≥70 mg/m 2) were randomly assigned to control regimen [ondansetron (O) 32 mg i.v. and dexamethasone (D) 20 mg p.o. on day 1; D 8 mg twice daily on days 2-4] or aprepitant (A) regimen (A 125 mg p.o. plus O 32 mg and D 12 mg on day 1; A 80 mg and D 8 mg once daily on days 2-3; and D 8 mg on day 4). The primary endpoint was overall complete response (no emesis and no rescue therapy over days 1-5). Data were analyzed by a modified intent-to-treat approach. Between-treatment comparisons for each gender were made using logistic regression. Main results: Women comprised 42 and 43% of the aprepitant and control groups, respectively. In the control group, 41% of women had overall complete response compared with 53% of men. In the aprepitant group, 66% of women had overall complete response compared with 69% of men. Conclusion: The addition of aprepitant may negate the adverse prognostic effect of female gender on the prevention of CINV in patients receiving highly emetogenic chemotherapy.