In a 33 year old man with no discernible immunologic defect, invasive aspergillosis developed in both the pericardium and lung with marked granulomatous reaction. The patient received 2 g of intravenous amphotericin B over eight weeks, with partial regression of the pulmonary infiltrate and disappearance of symptoms. However, five months later, he returned with marked progression of his disease. Evaluation of host defense, including granulocyte and lymphocyte function, was normal. The patient was given an additional 3g of amphotericin B over nine weeks with marked improvement in symptoms and chest roentgenogram. At six-month follow-up, he was asymptomatic with a stable radiographic appearance. A recurrence in symptoms and the pulmonary infiltrate was noted two months later. He was treated with an additional course of amphotericin and currently is receiving ketoconazole in hopes of suppressing the infection. We could find no immune impairment to explain the severe pulmonary and pericardial disease due to Aspergillus flavus in this young man.