Many studies have examined the etiology of fever complicating neutropenia. Little is known about the etiology of fever occurring immediately following recovery from myelosuppression. We reviewed 165 episodes of fever in patients who were admitted to the University of Pennsylvania Medical Center (Philadelphia) between 1 August 1992 and 15 August 1994 for the treatment of acute leukemia. We included patients who had episodes of fever (temperature of > or = 38 degrees C) for > or = 48 hours within 10 days after an absolute neutrophil count of < or = 500 cells/mm3 was determined. Twenty-nine (20%) of 145 episodes met these criteria. In 5 (17%) of 29 episodes the cause of fever was a bacterial infection, in 6 (21%) of 29 episodes the cause of fever was noninfectious, and in 12 (41%) of 29 episodes the cause of fever was unknown. Six (21%) of 29 episodes were due to documented or suspected fungal infection, four were due to suspected pulmonary aspergillosis, and two were due to systemic candidal infections. Fever following recovery from chemotherapy-induced neutropenia is common. Fungal infections occur frequently after recovery from myelosuppression despite widespread use of empirical and prophylactic antifungal therapy. Improved strategies for diagnosing and preventing fungal infections in patients who have fever following recovery from myelosuppression are clearly needed.