The records of 40 consecutive patients with newly diagnosed acute nonlymphocytic leukemia (ANLL) were reviewed to determine the risk of recurrent fungal pneumonia during multiple episodes of chemotherapy-induced granulocytopenia. Fungal pneumonias were diagnosed as proven or probable using defined pathologic, microbiologic, radiologic, and clinical criteria. Sixteen patients died without a complete remission; of these, all 11 who underwent autopsy were found to have invasive fungal pneumonia. The 24 patients who achieved a complete remission received one to nine (median, four) additional courses of intensive chemotherapy for remission consolidation and/or relapse, and experienced 132 episodes of severe granulocytopenia. Seven patients never had a pulmonary infection despite 34 granulocytopenic episodes. However, fungal pneumonia complicated 32 (33 percent) of 98 granulocytopenic episodes in the other 17 patients. Fifteen of the patients who achieved a complete remission had at least one episode of fungal pneumonia; 12 received further chemotherapy, and nine (75 percent) of these had a subsequent fungal pneumonia. In all, 17 (52 percent) of 33 subsequent granulocytopenic episodes experienced by patients with a prior fungal pneumonia were complicated by another fungal pneumonia. All four patients with a probable fungal pneumonia diagnosed antemortem who subsequently underwent autopsy were found to have invasive fungal disease. It would appear that patients with ANLL who have had one episode of fungal pneumonia are at high risk for recurrence during subsequent episodes of granulocytopenia. Empiric or even prophylactic amphotericin B therapy may be warranted for such patients.