Invasive fungal infections remain a common cause of morbidity and mortality among patients with leukemia who become further compromised by neutropenia. Candida and Aspergillus spp account for the vast majority of these infections, but other, less commonly recognized fungi can cause life-threatening infection in these hosts as well. The earlier, more limited antifungal armamentarium of ketoconazole, flucytosine, and amphotericin B has been substantially augmented by the availability of fluconazole, itraconazole, and the lipid-associated amphotericin formulations. Intense clinical study has focused on the use of these agents in empiric treatment, treatment of suspected or proven infection, and prophylaxis. Recognition of the limitations of antifungal therapy in the neutropenic host has led to evaluation of the adjunctive role of immunotherapy.