Photodynamic therapy (PDT) using hematoporphyrin derivative (HpD) has been performed in 139 lesions of 115 lung cancer cases since 1980. The efficacy of and indication for PDT were discussed in this paper. Twenty-six cases were early stage lung cancer and 17 were stage I, 11 were stage II, 42 were stage III and 19 were stage IV, respectively. Complete remission was obtained in early stage cases with small lesion, however incomplete remissions or tumor recurrences were observed in large extent lesions.Opening of obstructed bronchus was obtained in the advanced lung cancer cases and improvements of performance status were obtained. It was also possible to increase the operability and to reduce the extent of resection area in the advanced cases.This modality has more possibilities in the treatment of malignant tumors in future.