The antiemetic effect of ondansetron (Supplied by Qi Lu Pharmaceutical Company) in cisplatin-induced nausea and vomiting was studied in a randomized cross-over trial in 167 patients. The daily dose of cisplatin was 30mg for 5 days, 50mg for 3 days or 50mg/m2 for 1-2 days. The patients received randomly ondansetron, metoclopramide or Zofran (Glaxo) in the first cycle of the treatment and received the other antiemetic drug in the second cycle. The effective control rate of acute emesis (0-2 emetic episodes) was 86.6% in patients treated with ondansetron and 35.4% in those treated with metoclopramide. The mean frequency of vomiting was 1.1 times in ondansetron and 5.7 times in metoclopramide (P < 0.01). The results show that ondansetron (Qi Lu) is superior to metoclopramide for the control of acute or delayed emesis. The antiemetic effects of ondansetron (Qi Lu) and Zofram (Glaxo) are similar. The side-effects of ondansetron are mild.