Pulmonary blastoma are a family of tumors in which the glands or mesenchyme composing the neoplasm are primitive or emb yonal in appearance. We report a pulmonary blastoma occurring in a 31 years old man. An abnormal shadow was detected in the right lower lung field in a routine chest X-ray film. The preoperative imaging films showed about a 5cm sized well circumscribed solid tumor of the right lung. A preoperative clinical diagnosis of primary lung cancer was considerd. The operative field showed that the hard, round mass, 6$ imes$5$ imes$4cm in diameter was localized in middle lobe of the right lung, and partially adhered to the upper lobe, pericardium and diaphragm. Right middle lobe lobectomy, right upper lobe wedge resection, partial pericardiectomy and diaphragm resection with plication was performed with radical Iymph node dissection. Histopathologic diagnosis was pulmonary blastoma (Biphasic blastoma). It is considered that the prognosis of biphasic blastoma is worse than WDFA(well differentiated fetal adenocarcinoma). There are no other available treatments except for surgical resection. It is suggeste that it is necessary to collect as many cases as possible, to make definite classifications and to examine the clinical course and prognosis of pulmonary blastoma.