OBJECTIVE To determine the feasibility of adding paclitaxel to standard cisplatin/etoposide (EP) and thoracic radiotherapy. METHODS Thirty-one patients were enrolled onto this study. During the phase I section of this study, the dose of paclitaxel was escalated in groups of three or more patients. Cycles were repeated every 21 days. For cycles 1 and 2, paclitaxel was administered according to the dose-escalation schema at doses of 100, 135, or 170 mg/m(2) intravenously over 3 hours on day 1. Once the maximum-tolerated dose (MTD) of paclitaxel (for cycles 1 and 2, concurrent with radiation) was determined, that dose was used in all subsequent patients entered onto the phase II section of this study. For cycles 3 and 4, the paclitaxel dose was fixed at 170 mg/m(2) in all patients. On day 2, cisplatin 60 mg/m(2) was administered for all cycles. On days 1, 2, and 3, etoposide 60 mg/m(2)/d (cycles 1 and 2) or 80 mg/m(2)/d (cycles 3 and 4) was administered. Chest radiation was given at 9 Gy/wk in five fractions for 5 weeks beginning on day 1 of cycle 1. Granulocyte colony-stimulating factors were used during cycles 3 and 4 only. RESULTS Twenty-eight patients were assessable. The MTD of paclitaxel was 135 mg/m(2), with the dose-limiting toxicity being grade 4 neutropenia. Cycles 1 and 2 were associated with grade 4 neutropenia in 32% of courses, with fever occurring in 7% of courses and grade 2/3 esophagitis in 13%. Cycles 3 and 4 were complicated by grade 4 neutropenia in 20% of courses, with fever occurring in 6% of courses and grade 2/3 esophagitis in 16%. The overall response rate was 96% (complete responses, 39%; partial responses, 57%). After a median follow-up period of 23 months (range, 9 to 40 months), the median survival time was 22.3 months (95% confidence interval, 15.1 to 34.3 months) CONCLUSIONS The MTD of paclitaxel with radiation and EP treatment is 135 mg/m(2) given over 3 hours. In this schedule of administration, a high response rate and acceptable toxicity can be anticipated.