Pleuropulmonary blastoma (PPB) is an unusual intrathoracic blastoma presenting in childhood and charac-terized by a biphasic neoplastic population of undifferentiated, small round blastemal cells and larger spindle-shaped sarcomatous cells with entrapped benign epithelial-lined structures. We experienced the cytologic features of PPB in imprint smear from the pleural-based huge mass of the middle lobe of the right lung in a 4-year-old boy. The smears showed high cellularity composed of small ovoid blastemal elements and scattered spindle mesenchymal tumor cells. Lobectomy and pathologic investigation confirmed the diagnosis. PPB seems to be a tumor in which accurate diagnosis may be achieved by cytoiogy if appro-priate clinical information were given. Timely and accurate diagnosis of PPB by cytology paves the way for attempting preoperative treatment in future cases.