A pilot study of irinotecan hydrochloride(CPT-11)and cisplatin(CDDP)combination chemotherapy had been performed for previously treated non-small cell lung cancer. CPT-11(60 mg/m(2))and CDDP(30 mg/m(2))were administered on days 1 and 15 every 28 days, and the combination chemotherapy was repeated up to 4 courses. The efficacy and safety of this pilot study based on outpatient therapy were evaluated. Eleven patients were entered, and the median number of courses was 3 courses. Severe adverse reactions(grade 3 or higher)were 33% for neutropenia, and 9.1% for leukopenia, anemia, diarrhea, fatigue, and vomiting. A case with grade 3 diarrhea needed hospital admission for a short period, and thereafter outpatient therapy could continue. The efficacy of this study was 73% of SD and 27% of PD, and MST was 358 days. These results suggest that this protocol could be carried out as outpatient therapy, and may contribute to prolonged survival time.