Twenty-two patients were diagnosed as coexisting active pulmonary tuberculosis and lung cancer during last ten years until 1989. They were nineteen men and three women and their age ranged from 61 to 84 years with a mean age of 71.3. Six patients had history of tuberculosis, three had undergone gastrectomy and four patients were complicated with diabetes mellitus. Histological types of lung cancer were epidermoid cell carcinoma in 13, adenocarcinoma in 3, large cell carcinoma in 2, and small cell carcinoma in 4 and clinical stages were "stage I" in 2, "stage II" in 2, "stage IIIA" in 5, "stage IIIB" in 4 and "stage IV" in 7, except 2 patients after surgical treatment. Localizations of lesions of cancer and tuberculosis were in the same lobes in 6, in ipsilateral lung in 6, and in contralateral lung in 6, except 4 cases, whose lesion of tuberculosis was not detectable roentgenologically and all cancers of "same lobe" cases were peripheral origins. Although, the prognosis was poor, which reflects the prognosis of lung cancer as a whole, the efficacy of anti-tuberculous chemotherapy was as good as patients without lung cancer. We mainly discussed the diagnostic points to detect the coexistence of lung cancer and pulmonary tuberculosis at early stage.