We describe a rare case of a primitive neuroectodermal tumor (PNET) originating in the lung of a 28-year-old woman. A lung mass was detected incidentally on a chest radiograph taken before a Caesarian delivery. The chest P-A view showed a well-defined, lobulated mass in the right lower lobe with a small pleural effusion on the right. A thoracic CT with contrast enhancement showed a lobulated, heterogeneous, enhanced mass of approximately 9.2 x 8.4 x 6.3 cm with inner amorphous calcifications in the right lower lobe and a small right pleural effusion. A right lower lobectomy was performed 1 month after delivery. The pathology report was a primary pulmonary PNET with focal visceral pleural involvement.