A 57-year-old man was found to have a tumour in the right lower lobe of the lungs, which was not classifiable by biopsy. The tumour could only be partially removed by surgical resection. The diagnosis of a pulmonary blastoma was made from the resected tissue. Clinically, rapid progress occurred with invasion in the mediastinal space and the epigastrium. In spite of radiation therapy, the patient died about 2 1/2 months after surgery of respiratory insufficiency. Autopsy confirmed a pulmonary blastoma with extensive infiltration of the mediastinal space and upper abdomen as well as metastases in the regional lymph nodes, pleura, peritoneum, thyroid gland, heart and central nervous system. The present report of a pulmonary blastoma should draw attention to this extremely rare tumour. It should be included in the differential diagnosis, because the survival time can be increased if the correct diagnosis is made very early.