A case of a rare benign solitary pulmonary neoplasm of alveolar adenoma type in a 42-year-old man was presented. The tumor consisted of a glandular component which reacted with antibodies against cytokeratins CAM5,2, AE1-3 as well as against epithelial membrane antigen (EMA) in superficial parts of cytoplasmatic membrane, while actin and desmin were positive in the stromal component. Ultrastructurally, glandular component represented chiefly type II pneumocytes, while pneumocytes of type I occurred rarely. Stroma of the tumour consisted of myofibroblasts, fibrocytes, and collagen fibrils.