Aims and background: Based on the results of a preclinical study, a phase I trial was conducted to evaluate the feasibility of administering docetaxel followed by gemcitabine in non-small cell lung cancer patients. Study design: Sixteen patients with advanced non-small cell lung cancer (stages III B-IV) were treated on the 1(st) day with docetaxel and on the 8(th) day with gemcitabine. Treatment was repeated every three weeks for a maximum of six cycles. Five groups received docetaxel/gemcitabine (mg/m(2)): 50/800, 60/800, 60/900, 60/1,000, 70/1,000. All patients and 57 cycles were assessed for toxicity. Results: The most important side effects were grade IV neutropenia in 4 patients (2 at the 60/1000 level and 2 at the 70/1000 level) and grade III leukopenia and neutropenia without fever in 4 and 6 patients, respectively. Maximum tolerated dose was not reached. Conclusions: The sequence docetaxel-->gemcitabine appears well tolerated and easy to administer. For this reason, a phase II study is ongoing to fully assess its antitumor activity.