A phase II study was designed to evaluate objective response rate and toxicity of fotemustine as single-drug chemotherapy in non-small-cell lung cancer. Eighty-seven patients with unresectable non-small-cell lung cancer took part in the study. Seventy-seven were evaluable for response. Of these, 60% had received prior chemotherapy and 74% had metastatic disease. Moreover, 22 patients had central nervous system metastases (of whom 12 were evaluable for this site). Treatment consisted of fotemustine 100 mg m-2 administered on days 1 and 8 followed by a 5 week rest period. Afterwards, responding or stabilised patients received fotemustine 100 mg m-2 every 3 weeks as a maintenance therapy. Toxicity and quality of life were recorded during therapy. Thirteen patients (17%; 95% CI 9-25%) had an objective response (11% for pretreated, 26% for non-pretreated) with a median duration of 22 weeks (range 7-41 weeks). Two objective responses were observed among the 12 patients with evaluable brain metastases. No response was observed among the 14 patients with adenocarcinoma. Haematological, gastrointestinal, hepatic and renal toxicities were mild to moderate and manageable. The most frequent biological adverse reactions were delayed thrombocytopenia and neutropenia. Quality of life did not significantly decrease during the first 6 treatment weeks. Moreover, it remained stable during the study period in patients with response or stabilisation, whereas it significantly decreased in patients who experienced progression of the disease. Fotemustine is feasible for single-drug chemotherapy in non-small-cell lung cancer even though poor prognostic variables such as brain metastases are present. It can be administered on an outpatient basis and toxicity is moderate and manageable. Thus, fotemustine can be considered as a putative drug in further combinations.