The aim of the present study was to determine the clinical activity and toxicity of a novel chemotherapy combination regimen of gemcitabine, ifosfamide and cisplatin (GIP), administered every 3 weeks, in patients with inoperable non-small cell lung cancer (NSCLC). From October 1998 to July 1999, Is previously untreated stages IIIb (4) and IV (14) patients were enrolled into the study. Gemcitabine and ifosfamide (with mesna as uroprotection) was administered on days 1 and 6, at a dose of 1000 and 1500 mg/m(2), respectively; and cisplatin was given on day 1 at a dose of 60 mg/m(2), every 3 weeks. All 18 patients were evaluable for response and toxicity profiles. One patient achieved a complete response, and 11 patients achieved a partial response, with an overall response rate of 66.7% (95% CI, 45-89%). The main toxicity was hematological, a NCI grade 3-4 neutropenia in 16 patients (88.9%) during the treatment course. Febrile neutropenia occurred in three patients (16.6%). Grade 3 anemia occurred in eight patients (44.4%) and grade 3-4 thrombocytopenia occurred in 11 patients (61.1%). Non-hematological toxicity was mild and tolerable. No toxic death occurred. The median survival was 12.7 months and 1 year survival was 58.4%. The GIP combination chemotherapy produced a high response rate in advanced NSCLC; however, there was a relatively high percentage of hematological toxicity that still could be tolerated. A randomized trial comparing GIP to a two-drug combination of gemcitabine and cisplatin is planned.