A 49-year-old man was admitted to our hospital with a productive cough and bloody sputum. Peripheral blood eosinophil counts and serum IgE values were elevated. Chest radiography and chest computed tomography revealed a solitary nodule with cavitation and satellite lesions in the right middle lobe, in contact with the pleura. The diagnosis of paragonimiasis westermani was confirmed by detection of ova in the sputum and bronchoalveolar lavage fluid (BALF) samples, and by immunoserological examination. The patient was treated with praziquantel for 3 days at a daily dosage of 75 mg/kg. After treatment, his clinical symptoms and radiological abnormalities disappeared. The IL-5 level was high in BALF, but it was undetectable in the plasma, suggesting that IL-5 in inflammatory lesions may be particularly important in mediating eosinophilia in the blood and BALF in paragonimiasis westermani.