This randomised, single-blind, parallel-group study was carried out in 48 French pneumology centres to compare the anti-emetic efficacy of ondansetron and an alizapride plus methylprednisolone (ALI/MPS) combination in patients receiving high-dose cisplatin. A total of 220 patients were recruited of whom 209 were evaluable (100 on ondansetron and 109 on ALI/MPS). Thirty minutes before cisplatin, patients received either ondansetron (8 mg i.v.) or alizapride (4 mg/kg i.v.) combined with methylprednisolone (500 mg i.v.). The ondansetron and alizapride injections were repeated 4 and 8 h later. Thereafter, patients received oral ondansetron (8 mg) or alizapride (50 mg) 3 times daily for 5 days. Ondansetron was significantly superior to ALI/MPS in the control of acute emesis (p less than 0.001); 88/100 (88%) of ondansetron, and 69/109 (63%) of ALI/MPS patients experienced less than 3 emetic episodes. Similarly, ondansetron was superior to ALI/MPS for the control of acute nausea (visual analogue scale at 24 h; 13 vs. 22 mm respectively, p = 0.0012). The superiority of ondansetron over days 2-6 was not as great as that over the first 24 h, although there was a trend in favour of ondansetron. More patients treated with ondansetron wished to take the same anti-emetic treatment again (83% for ondansetron vs. 56% for ALI/MPS, p less than 0.001). Both treatments were well tolerated. This study shows that ondansetron is superior to a benzamide-corticosteroid combination in the control of acute cisplatin-induced emesis.