We report the case of a 32-year-old man with a mycotic aneurysm of the left subclavian artery. This patient had immunosuppression caused by chemotherapy administered for treatment of leukemia. This aneurysm was revealed by two episodes of hemoptysis caused by a lung parenchyma fistulization. The patient was treated successfully by simple ligation and exclusion via a thoracotomy with partial lung resection. Histologic examination confirmed the presence of aspergilloma filaments in the false aneurysm. We suspect that aspergilloma could have been the cause of the mycotic aneurysm in this particular case. The literature on subclavian artery mycotic aneurysms is reviewed. (J VASC SURG 1995;21:697-702.)