Pleuropulmonary blastoma (PPB) is an unusual intrathoracic blastoma presenting in childhood and characterized 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 cytology if appropriate clinical information were given. Timely and accurate diagnosis of PPB by cytology paves the way for attempting preoperative treatment in future cases.