To evaluate the efficacy and toxicity of weekly docetaxel (D) as II line treatment in non-small cell lung cancer (NSCLC), in November 1999, we started a phase II study on advanced (stages IIIB-IV) NSCLC patients pre-treated with at least one platinum-based chemotherapy regimen with or without radiotherapy. The schedule consisted of D 40 mg/m(2), weekly for 6 weeks, followed by a rest period of 2 weeks, for three cycles or until progression. Eligibility criteria were: histopathologic diagnosis of NSCLC; age <or=75 years; evaluable or measurable progressive lesions; PS (ECOG) 0-2; adequate haematology and biochemistry parameters; no serious concurrent diseases; no symptomatic brain lesions; and informed consent. The end points were assessment of overall response rate, toxicity and quality of life (QoL). Patients were re-evaluated at the end of every cycle. An interim analysis of 18 patients (16 M) was performed. Weekly courses were 132; 16 of 18 patients were evaluable for response and 17 of 18 for toxicity. Two of the 16 patients (12.5%) had a partial response (95% CI: 10.5-14.7%). Haematological toxicity was very mild: grade 1-2 neutropenia occurred in four patients, grade 3 neutropenia in two patients; grade 1-2 anaemia in four patients; and grade 1-2 thrombocytopenia in two patients. Non-haematological toxicity was also very mild, with the exclusion of asthenia (grade 1-2 in ten patients and grade 3 in five patients) and alopecia (grade 1-2 in seven patients and grade 3 in eight patients). No cases of grade 4 toxicity were observed. No QoL evaluations were reported in this interim analysis. In conclusion, these preliminary data confirm that weekly D results in tolerable toxicity in pre-treated NSCLC. Myelo-suppression, the dose-limiting toxicity of every 3 week schedules, is not a clinically relevant problem when D is administered weekly. G-CSF was used only sporadically in four patients, and no febrile neutropenia was reported. Patients were pre-treated with dexamethasone and no allergic reactions were seen. Although the therapeutic activity appears to be comparable to that of every 3 week schedules, more data are necessary before definite conclusions can be drawn. Accrual of patients is still ongoing.