BACKGROUND A phase II clinical trial was performed to evaluate the activity and toxicity of bimonthly cisplatin and weekly 24-h infusion of high-dose 5-fluorouracil and leucovorin in patients with advanced gastric cancer. METHODS From September 1997 to March 1998, 23 chemo-naive patients of advanced gastric cancer were enrolled in this study. The regimen consisted of weekly 24-h infusion of 5-FU (2,600 mg/m2) and LV 150 mg and bimonthly cisplatin (25-50 mg/m2) bolus for 12 weeks followed by a 2-week break. RESULTS There were 10 male and 13 female patients with a median age of 52 years. A total of 428 chemotherapy treatments were given with a mean of 11. Seventeen patients were evaluable for response. There were 41% (7/17) partial response, 18% (3/17) stable disease and 41% (7/17) progressive disease. The grade III or IV toxicity included anorexia 35% (8/23), fatigue 26% (6/23), vomiting 17% (4/23) and mucositis 9% (2/23). One patient developed perforated duodenal stump after chemotherapy. One patient died of hyperammonemia-related coma. The median times to disease progression and overall survival were 3.5 and 7 months, respectively. CONCLUSIONS This regimen showed modest activity against gastric cancer. However, there was no survival advantage and there was greater toxicity than with weekly high-dose 5-FU-LV alone.