A 63-year-old man, who had had operation for the treatment of pulmonary tuberculosis 40 years before the present disorder, was admitted to our hospital with massive hemoptysis. Radiologic examinations showed a mass shadow with a crescent air sign resembling aspergilloma. Operative exploration showed a well-encapsulated retained surgical sponge between the middle and lower lobes. A bronchial fistula was present in the lower lobe. The appearance of the crescent air sign was caused by drainage of exudative effusion around the retained sponge. Intrathoracic retained surgical sponges associated with bronchial fistula should be included in the differential diagnosis of patients who have mass shadows with crescent air signs but no evidence of Aspergillus infection, and who have a history of thoracotomy.