Pulmonary blastoma is a rare tumour of the lung composed of epithelial and mesenchymal elements that morphologically resemble the embryonal structure of the lung. The authors report a 79-year-old man who was diagnosed with a pulmonary blastoma within bronchioloalveolar cell carcinoma. Macroscopic, histopathological and immunohistochemical findings suggested that the pulmonary blastoma was closely associated with the bronchioloalveolar cell carcinoma.