Between July 1973 and June 1981 systemic fungal infections were found in 27 of 270 autopsies of patients with hematologic malignancies: in 16 aspergillosis, in 6 candidiasis, in one aspergillosis and candidiasis, and in 4 mucormycosis. The frequency increased from 6% during the first 6 years to 25% during the last 2 years (p = 0.025). Fever despite antibiotics and new pulmonary infiltrates were the major symptoms. In only 6 of 16 patients did microbiological findings support the clinically suspected diagnosis. Systemic fungal infections were the principal cause of death in 12 patients. Because of the difficulty of establishing the diagnosis, empiric antimycotic therapy should be started promptly on clinical suspicion in patients with neutropenia and fever despite antibiotics.