We report two cases with small cell lung cancer (SCLC) receiving multicyclic dose-intensified chemotherapy (DI-CT) supported by autologous blood progenitor cell transplantation (ABPCT). Both cases were initially treated with cisplatin (CDDP), etoposide (ETP) and concurrent thoracic irradiation, however they had recurrent disease within a year. After receiving conventional chemotherapy, they underwent multicyclic DI-CT consisting of CDDP, ETP and ifosfamide supported by G-CSF and ABPCT. Definite regression of the tumors was observed. Severe neutropenia and thrombocytopenia were encountered but they were reversible and no life-threatening complications were experienced. These results suggest the feasibility and effectiveness of multicyclic DI-CT and the usefulness of ABPCT as a treatment option for relapsed SCLC.