An 82-year-old man with extensive small cell lung cancer was treated with 2 courses of low dose CPT-11 (40 mg/body, day 1, 8 and 15) and carboplatin (100 mg/body, day 1). The reduction in tumor sizes evaluated by two-direction measurement was 88%. His creatinine clearance rates before and after chemotherapy were 20 and 28 ml/min, respectively. Temporary leukopenia (900/microl) during the second course of chemotherapy was quickly reversed by the administration of G-CSF, without any episode of infection. Low dose CPT-11 and carboplatin seems to be a promising regimen for elderly patients with small cell lung cancer and renal dysfunction. Cancer tends to increase in old age groups. We consider that it is necessary to examine ideal low dose chemotherapies that can be effective yet preserve quality of life.