Using a day 1 and 8, every-3-week schedule, our purpose was to determine the maximum tolerated dose of irinotecan (CPT-11, Camptosar) that can be administered immediately after gemcitabine (Gemzar) at a dose of 1,000 mg/m² IV. In this phase I trial, the maximum tolerated dose was defined as the dose level immediately below the level in which two of the first three patients in any cohort, or at least two of six patients in any expanded cohort, experienced dose-limiting toxicity. Dose-limiting toxicity pertained only to toxicity during the first cycle of treatment. Escalation of irinotecan was planned in groups of three patients, with three additional patients added at the first indication of dose-limiting toxicity. A total of 19 patients have been enrolled.