Only a minority of patients with hepatocellular carcinoma (HCC) may benefit from curative treatments, whereas there is no standard therapy for the remaining patients. The objective of this multicentre, open label phase II study was to estimate the objective tumour response rate of a 28-day regimen of oral eniluracil/5-fluorouracil (5-FU) in patients with chemotherapy-naïve, or anthracycline-refractory, inoperable HCC. 45 patients received courses of twice daily oral 5-FU (1.0 mg/m(2)) and eniluracil (10 mg/m(2)) for the first 28 days of each 5-week course. Patients were assessed at regular intervals to determine the tumour response and to evaluate toxicity. Patients were followed-up for a minimum of 6 months. No patient showed a partial or complete tumour response, and 18 patients (40%) had a best response of stable disease (95% confidence interval (CI) 25%, 55%). The median duration of progression-free survival (PFS) was 13.7 weeks (95% CI 10.0-20.0 weeks), and the median duration of overall survival (OS) was 50.3 weeks (range 1.1-64.1+ weeks). The combination of eniluracil/5-FU was well tolerated and had an acceptable safety profile. Only 7 patients (16%) reported at least one adverse event (AE) of grade 3 or 4 intensity considered reasonably attributable to the study medication. In conclusion, oral eniluracil/5-FU had minimal, if any, activity in patients with inoperable HCC, but the safety profile was acceptable.