A phase II trial of 5-fluorouracil (5-FU) [250-450 mg/m2/day x 5 days as an intravenous (IV) bolus] combined with calcium leucovorin (500 mg/m2/day x 5 1/2 days by continuous IV infusion) administered on a 28-day schedule was performed in 15 patients with advanced hepatocellular carcinoma. The median age was 58 years; performance status ranged from 50 to 100%. Of 15 evaluable patients, 1 (7%) had a partial response lasting 2.4 months; 8 (53%) had stable disease with a median duration of 5.7 months; and 6 (40%) had progressive disease with a median time to progression of 2.7 months. Median survival was 3.8 months. Treatment with 5-FU and calcium leucovorin was moderately well tolerated; 9% of the treatment courses were complicated by grade 3 or 4 hematological toxicity, and 10% of the courses were complicated by grade 3 or 4 gastrointestinal toxicity. Despite the efficacy of the combination of 5-FU and leucovorin in advanced colorectal cancer, our results document the general resistance of hepatocellular carcinoma to modulated 5-FU.