Fibrosing mediastinitis due to Aspergillus is rare, particularly in the immunocompetent host. Fibrosing mediastinitis due to Aspergillus species in the immunocompetent patient can be indolent and may be treated with antifungal therapy rather than surgery. We present a 78-year-old nonsmoking, nondiabetic woman with chronic fibrosing mediastinitis due to Aspergillus. Multiple attempts at securing a tissue diagnosis were inconclusive. Ultimately, Aspergillus infection was diagnosed by a video-assisted thoracoscopic surgical biopsy. The patient was started on oral voriconazole, and she remains clinically stable with radiographic improvement. A prolonged, perhaps lifelong, course of antifungal therapy is planned.