This phase II study was conducted to determine the efficacy and toxicity of a gemcitabine (GEM) and oxaliplatin (OX) chemotherapy protocol in patients with unresectable biliary tract cancer (BTC). Patients were treated with GEM 1000 mg m-2 (30 min infusion) on days 1, 8, 15, and OX 100 mg m-2 (2 h infusion) on days 1 and 15 (gemcitabine and oxaliplatin (GEMOX-3 protocol), repeated every 28 days. The data were collected according to the Simon 2-stage design for a single centre phase II study (alpha=0.05; beta=0.2). Primary end point was response rate; secondary end points were time-to-progression (TTP), median survival, and safety profile. Thirty-one patients were enrolled in the study between July 2002 and April 2005. Therapeutic responses were as follows: partial response in eight patients (26%, 95% confidence interval (CI) 14-44), stable disease in 14 patients (45%, 95%CI 29-62), resulting in a disease control rate of 71%. Nine patients (29%, 95%CI 16-47) had progressive disease. Median TTP was 6.5 months. Median overall survival was 11 months. Common Toxicity Criteria (CTC) Grade 3-4 toxicities were transient thrombocytopenia (23%), peripheral sensory neuropathy (19%), leucopenia (16%), and anaemia (10%). In conclusion the GEMOX-3 protocol is active and well tolerated in patients with advanced BTC. It can be applied in an outpatient setting with three visits per month only.