A case report on a 64-year-old male with pulmonary dirofilariasis cytologically mimicking lung cancer is presented. By transbronchial brushing cytology, several suspect cells with a papillary arrangement showing a high nuclear/cytoplasmic ratio, irregularity of nuclear shape, nuclear enlargement and a macronucleolus were obtained. These cells seemed to originate in the reparative process of the bronchiolar epithelium around the infarcted lesion containing Dirofilaria immitis.