We conducted a phase II evaluation of fazarabine 1.75-2.0 mg/m2/hr over 72 hours every 28 days in 14 previously untreated patients with advanced adenocarcinoma of the pancreas. The initial dose was 1.75 mg/m2/hr in 10 patients, and 2.0 mg/m2/hr in 4 patients. The dose was escalated in 8 patients, including all 4 who started at the higher dose level. Toxicity was unexpectedly mild. The median WBC nadir was 4.4 (range: 2.4-15.8) x 10(3)/microliters, the median absolute neutrophil nadir was 3.2 (range: 0.9-13.0) x 10(3)/microliters, and the median platelet count was 134.0 (range: 48.0-291.0) x 10(3)/microliters. Gastrointestinal toxicity was generally mild. No major responses were seen, excluding, with 95% confidence, a response rate in excess of 20%.