Our purpose was to determine the efficacy of irinotecan plus paclitaxel administered on day 1, repeated every 2 weeks, in untreated patients with advanced or metastatic non-small-cell lung cancer (NSCLC). In total, 56 patients with inoperable or metastatic stage III and IV NSCLC with a histologically or cytologically confirmed diagnosis were enrolled. None of the patients had undergone prior chemotherapy or radiation therapy. Treatment involved irinotecan 125 mg m À2 and paclitaxel 135 mg m À2 administered on day 1 and repeated every 2 weeks for a planned number of nine cycles. With a standard dose of paclitaxel at 135 mg m À2 , the dosage of irinotecan was escalated at four levels: 75, 100, 125 and 150 mg m À2 ; 125 mg m À2 was established as the maximum tolerated dose; this dosage was administered to 46 patients. A total of 52 patients (median age 65 years, range 38 -77 years) were assessable for toxicity and survival and 46 for response rate. Out of 46 evaluable patients, 19 achieved partial response (41.3%), 17 had stable disease (37%) and 10 (21.7%) experienced disease progression. The median duration of response was 6 months (range 2 -9 þ months). The main adverse reactions were myelotoxicity (grades 3 and 4) in 10 (19.2%) patients and diarrhoea (grade 3) in four (7.7%) patients. Irinotecan combined with paclitaxel, administered every 2 weeks, appears to be an effective treatment for advancedstage NSCLC.