Nausea and vomiting are common side effeets of most cytotoxic agents, eisplatin being the most emetogenic. All patients given high doses of eisplatin will vomit in the 24 hour following its administration unless antiemetics are given. However, none of the currently available antiemeties are entirely effective. Ondanstron is a new selective 5-HT, receptor antagonist which has been shown to be effeetive in preventing acute emesis induced by a variety of chemotherapy and radiotherapy regimens. We gave ondansetron to 20 gynecological eancer patients who were receiving cisplatin containing combination chemotherapy. This study was undertaken to evaluate the efficacy of ondansetron in preventing nausea and vomiting induced by cisplatin containing regimen, and related side effects. Primary neoplasms were as following; ovarina carcinomas ll, cervical carcinomas 8, and vaginal carcinoma 1. Cyclophosphamide and/or adrimaycin were combined with eisplatin(50mg/M2). Ondansetron at dose of Hrng(4ml) was given as a slow intravenous injection prior to the administration of eisplatin, and then given aa two further Smg doses as slow intravenous injeetions 4 and 8 hours after the start of first dose. On day 2, ondansetron was given as a slow intravenous injection at a dose of Rmg twice daily, and during day 3-6, given orakly by Rmg twice. On day 1, nausea was controlled in 55% of patients(none 30%, mild 25%), and vomiting controlled in 60%(complete 40%, major 20%). On day 2-6, vomiting was controlled in 45% of patients(complete 20%, major 25%) Ondansetron related side effeets were mild with general weakness 20%, headache 15%, abdominal pain 10%, chillness 10%, dizziness 5%, flushing 5%, anxiety 5% and palpitation 5% The results showed that ondansetron is effective in control of cisplatin induced nausea and vomiting, and can be adminstered safely with minimal side effects, but prolonged intrauenous injeetion of ondans-etron is recommended in patients with delayed emesis.