In order to assess the effectiveness of sequential TI for the treatment of LD SCLC, we analyzed 69 patients who had received CAV-PVP chemotherapy consisting of cyclophosphamide, adriamycin, vincristine, cisplatin and etoposide, plus sequential TI between 1986 and 1992. TI was delivered at a total dose of 50 Gy, 5 fractions/week for 5 weeks, once patients achieved a maximal response to chemotherapy. Responding patients also received PCI at a total dose of 30 Gy, 5 fractions/week for 3 weeks. Thirty patients achieved CR by chemotherapy and an additional 10 achieved CR after TI, resulting in a CR rate of 58.0%. Of 40 patients achieving CR, 24 have relapsed so far; the primary (in 15) and the brain (in 4) were the major sites of relapse despite TI and PCI. The median survival time was 18.4 months, with a 2-year survival rate of 39% and 3-year survival rate of 20%. Almost all the patients encountered grade 3 or grade 4 leukopenia while receiving chemotherapy, but the toxicity of TI was generally mild. This treatment is useful for patients with LD SCLC.