OBJECTIVE To determine the antitumor activity and toxicity of paclitaxel administered as a 3-hour infusion in patients with advanced non-small-cell lung cancer (NSCLC). METHODS Fifty-one patients with advanced measurable or assessable NSCLC and performance status 0 to 2 who had not received prior chemotherapy were treated with paclitaxel 175 mg/m2 over 3 hours with premedication. Cycles were repeated every 3 weeks for a maximum of nine cycles. Most patients had prior radiotherapy (57%), extrathoracic metastatic disease (65%), and measurable disease (75%). Twenty-two percent had previously untreated stage III disease. RESULTS The objective response rate was five of 51 (10%; 95% confidence interval, 3% to 21%). No subgroup with a higher response rate could be identified. There were no complete responses (CRs) and all responses lasted less than 5 months. Treatment was well tolerated with brief World Health Organization (WHO) grade IV neutropenia in only 16% of patients. Grade III/IV myalgia/athralgia occurred in 22% of patients. No significant hypersensitivity reactions occurred. CONCLUSIONS The antitumor activity of this dose and schedule appears inferior to that reported in previously published phase II trials in NSCLC that used higher doses of paclitaxel infused over 24 hours, although confidence intervals for response overlap. Determining the optimal dose and schedule for using paclitaxel in NSCLC requires further investigation, and these results should caution against using shorter infusions outside appropriate clinical trials.