Recent advances in the chemotherapy of malignant diseases, particularly, in hematopoietic malignancies, has opened oncologists' eyes in wonder, whereas the chemotherapy of solid malignant diseases including the carcinoma of the lung is not satisfactory compared with the results of other modalities such as radiotherapy and surgery. The chemotherapy, however, gradually becomes a great importance because the majority of the cases of lung cancer is that of advanced one. Between June, 1974 and December 1980 we experienced 54 inoperable cases of lung cancers among which there were 11 cases diagnosed as an anaplastic carcinoma. The combination chemotherapy of vincristine (1 mg/body, iv, day 1), methotrexate (30 mg/body, iv, day 1 and 5), ACNU (100mg/body, iv, day 2) and adriamycin (40mg/m2, iv, day 2) was employed. Vincristine and methotrexate were given every 3 weeks and ACNU and adriamycin were repeated every 9 weeks. If the moderate degree of neuropathy due to vincristine occurred it was suspended and methotrexate was stopped if WBC was less than 2000/mm or if patients were suffered from stomatitis which disturbed their swallowing. According to the response criteria of Koyama-Saito 4, cases were responded and one of them survived 17 months after the initiation of above 4-drug combination chemotherapy, although she received another combination chemotherapy because of the relapse of disease. The combination chemotherapy of ACNU and adriamycin was tried to utilize the advantage of their time different effects on the bone marrow suppression and to cover heterogenous histopathological diagnosis of anaplastic carcinoma. The heterogeneity of anaplastic carcinoma included undifferentiated squamous cell carcinoma, adenocarcinoma, large cell carcinoma and even small cell carcinoma. In taking consideration of these points, the drug-combination was designed. Clinically, however, the long resting period made the tumor regrow in some cases due to severe delayed myelosuppression by the combination of ACNU and adriamycin. Thus, more cautiously-designed combination should be considered.