Systemic fungal infections are becoming increasingly common in patients with hematologic malignancies receiving antineoplastic therapy. The presence of acute myeloid or acute lymphoid leukemia, plus the use of chemotherapy to totally ablate malignant bone marrow cells, puts patients in a protracted neutropenic state. During this profound and prolonged neutropenic phase, patients receive antibiotic therapy for suspected or identified bacterial infections. However, when fever or other signs of infection continue despite antibiotic therapy, patients frequently need to be treated for suspected or identified systemic fungal infections. These infections may occur in patients receiving either standard antileukemia therapy or research protocol therapy involving new drugs, new drug combinations, higher doses, or newer schedules of established drugs. After antifungal therapy is initiated, it may be continued postdischarge in outpatient or homecare settings. Therefore, becoming knowledgeable about antifungal therapy is important for all oncology nurses regardless of practice setting.