This phase II trial assessed the antitumoral activity and toxicity of docetaxel 50 mg/m (1-h i.v. infusion) administered every 2 weeks as second-line treatment in 45 patients with advanced non-small cell lung cancer (NSCLC). A total of 251 infusions (median 4 per patient) were administered. The actual and relative median dose intensity values were 24.2 mg/m/week and 0.97, respectively. Thirty-seven patients were evaluable for tumor response. The overall response rate was 20% [95% confidence interval (CI) 8-32%] and included one complete response (2%) and eight partial responses (18%). Stable disease was found in seven patients (16%). With a median follow-up of 4 months, the median time to disease progression was 2.8 months (95% CI 1.9-3.7), the median overall survival was 4.0 months (95% CI 3.4-4.6) and the 1-year survival rate was 23% (95% CI 9-37). The every-2-weeks docetaxel schedule was well tolerated. Grade 3/4 non-hematological toxicities showed rates of 5% or less of patients and 2% or less of cycles. The main grade 3/4 hematological toxicity was neutropenia (16% of patients and 8% of cycles). No febrile neutropenia was found. Nevertheless, one toxic death was reported. We conclude that the biweekly docetaxel schedule showed an antitumoral activity similar to that found with the every-3-weeks or weekly docetaxel schedule in a second-line setting for advanced NSCLC. This antitumoral effect was associated with a marked reduction in hematological toxicity, therefore suggesting that this new docetaxel schedule might be useful in the design of combined second-line schedules for treating NSCLC.