Chemotherapy treatment for advanced pancreatic cancer is universally disappointing. Evidence suggested the possibility of improved activity of 5-fluorouracil (5-FU) in this disease when administered by continuous infusion in combination with interferon-alpha. Thirteen patients who had histologically documented stage III and IV adenocarcinoma of the pancreas were treated with 5-FU, 250 mg/m2/day by continuous infusion, in combination with interferon-alpha, 3 million units subcutaneously 3 times per week. Treatment was adjusted for toxicity and was continued until disease progression, unacceptable toxicity, or 8 weeks after a complete response. Responses were documented on two separate occasions that were separated by 4 weeks. Eleven men and two women were treated an average of 48 days. There was one responder, for a response rate of 7.7% (95% confidence interval, 0.1%-36%). The duration of response was 90 days. The median survival of the entire group was 8.3 months. Toxicity was significant, with more than 50% of patients requiring treatment breaks and dosage reductions. The most common toxicities were mucositis, hand-foot syndrome, diarrhea, and nausea. There were no treatment-related deaths. Treatment of advanced adenocarcinoma of the pancreas with continuous-infusion 5-FU and interferon-alpha is associated with significant toxicity without significant evidence of response.