Twenty-four cases of lung cancer, mainly of advanced cases and seven cases of metastatic lung tumors were treated with Bleomycin in combination with fibroblast-inhibiting agents such as chloroquine, phytonadione and prednisolone, and following results were obtained. 1) Of 24 lung cancers, 14 cases were evaluated by the chemotherapy evaluation standard adopted by the Japan Society For Cancer Therapy and "improvement" in 4 cases, "no change" in 8 cases and "aggravation" in 2 cases. The effects evaluated with histlogical types included "improvement" in 2 cases of 4 epidermoid carcinomas, but "no improvement" in adenocarcinomas and in undifferentiated carcinomas. 2) Of 7 metastatic lung tumors, 4 cases were evaluated, and "improvement" was obtained in a case of uterus carcinoma origin. 3) The side effects of Bleomycin were changes of skin such as pigmentation or sklerosis in 7 cases, phlebitis, fever and pulmonary disorder in 3 cases each, epilation and anorexia in 2 cases and stomatitis in 1 case. Of these side effects, pulmonary disorder must be paid careful attention and early detection of its occurrence is required and combination of fibroblast-inhibiting agents is believed necessary for the prevention of its occurrence.