The prognosis of advanced biliary tract carcinoma is poor with chemotherapy limited to a palliative role. This randomised study was designed to evaluate the effectiveness of a new liposomal thymidylate synthase inhibitor (TSI), OSI-7904L, in parallel with a modified de Gramont regimen of 5-FU/LV in patients with advanced biliary cancer. Patients with previously untreated advanced or metastatic carcinoma of the biliary tract were randomised to receive either OSI-7904L 12 mg/m2 intravenously every 21 days or a modified de Gramont schedule of 5-FU/LV (intravenous l-LV 200 mg/m2, bolus 5-FU 400 mg/m2 and a 46-h infusion of 5-FU 2,400 mg/m2) every 14 days. Twenty-two patients were randomised, 11 to each group. No patients responded in the OSI-7904L arm, while one patient achieved a partial response in the 5-FU/LV arm. The rates of disease stabilisation were 4/11 (OSI-7904L) and 10/11 (5-FU/LV). Both treatment arms were generally well tolerated. These results show that the activity of OSI-7904L is below a level of clinical relevance in advanced biliary tract cancer, providing only a small degree of disease stabilisation. A simplified de Gramont schedule appears to have marginally more activity. Both treatments were well tolerated.