The purpose of the present trial was to determine the activity of gemcitabine as a second-line chemotherapy for non small cell lung cancer (NSCLC). To be eligible, patients had to have pathologically proven NSCLC that has failed to respond to a first-line chemotherapy with a cisplatin-containing regimen, a Karnofsky performance status greater than 50 and adequate renal, haematological and hepatic functions. After registration, patients were treated by gemcitabine given i.v. at a dose of 1 g/m(2) on days 1, 8, 15 every 4 weeks. Response was assessed after two courses of therapy. Eighty-two patients have been registered, five are ineligible and 65 are assessable for response. Four partial responses were observed (6%). No change was documented in 18 cases (28%). Tolerance was good. A few grade III leucopenia and grade III-IV thrombopenia were observed. We conclude that gemcitabine has a modest activity as second-line chemotherapy for NSCLC. It has the advantage to be well tolerated and may thus be one drug to be proposed to the patients who have disease progression after a first-line chemotherapy and who ask for further treatment.