The antiemetic effect of ondansetron (supplied by Qilu Pharmaceutical Company) in patients receiving non-cisplatin chemotherapy (containing CTX and/or ADM) was studied in a multiple centre, randomized cross-over trial. The patients who had vomiting in the first turn of chemotherapy entered the trial. The patients received randomly ondansetron or control drugs-metoclopramide or Zofran (Glaxo) in the second turn of chemotherapy. In the third, the patients were cross-over to use the other antiemetic drug. A total of 155 patients were enrolled into the study. The results showed, the effective control rate (0-2 emetic episodes) on the first day were 87.7% of patients treated with ondansetron and 61.6% treated with metoclopramide. The mean frequency of vomiting was 0.8 times in ondansetron and 2.7 times in metoclopramide (P < 0.01). Ondansetron was superior to metoclopramide for the control of emesis. The antiemetic effects of ondansetron (Qilu) and Zofran (Glaxo) were very similar. The side-effects of ondansetron were mild.