There is no standard chemotherapy option for patients with biliary tract cancers. These patients present fairly ill and can have a rapid progression of disease. We conducted a multi-center, phase-II trial for patients with locally unresectable or metastatic bile duct or gallbladder adenocarcinomas using a modified regimen of gemcitabine and cisplatin to potentially improve tolerability. Patients received a 21-day treatment cycle of gemcitabine at 1,000 mg/m2 and cisplatin at 30 mg/m2 on days 1 and 8. To participate, 33 patients signed informed consent, and 30 patients received at least one dose of chemotherapy. By intention-to-treat analyses, 7 patients (21%) experienced a partial response and another 12 (36%) had stable disease for at least 12 weeks. The median progression-free survival was 6.3 months and median overall survival was 9.7 months. After 1 year, 39% of patients were alive. Most common grade 3-4 toxicities included neutropenia (33%), thrombocytopenia (23%), anemia (20%), nausea (20%), emesis (13%) and fatigue (10%). Of note, 52% of patients withdrew from study treatment, principally due to treatment-related adverse events. We concluded that this modified regimen appeared to have comparable activity to other gemcitabine and cisplatin regimens against advanced bile duct and gallbladder cancers, but there was still moderate toxicity in this patient population.