Fifty-seven patients with advanced gastric carcinoma were randomized to receive 15 mg/kg/week of 5-fluorouracil by either the iv or oral route. Toxic effects of treatment included nausea and vomiting (40% with the oral route versus 35% with the iv route) and myelosuppression, with a wbc count of less than 4000/mm3 (28% with the oral route versus 32% with the iv route). The frequency of partial response was 12% (three of 25 patients) for the oral route and 16% (five of 32 patients) for the iv route. Only two of 36 patients with liver metastases responded. No advantage was seen for the oral versus the iv route of 5-fluorouracil in the treatment of advanced gastric carcinoma.