A 66-year-old woman was admitted on May 13, 1989, because of an abnormal round shadow in the right hilum on chest X-ray film. Bronchoscopy revealed a stenosis of the right B8 caused by a bulging lesion. An aortogram showed a large meandering bronchial artery and a saccular aneurysm. The aneurysm was about 25 mm in diameter and associated with a bronchopulmonary anastomosis. It was surgically removed by right lower lobectomy. Pathological examination proved that the resected lesion was an arterial aneurysm. Patchy arteriosclerotic change was present in the intima of the aneurysm, but there was no evidence of inflammatory change in the arterial wall and the adjacent alveoli and bronchi. Twenty-six cases of bronchial artery aneurysm have been previously reported in the literature, but this is the first case that appeared as a solitary nodule on conventional chest X-ray.