Fungal infections are common and serious complications of AIDS; nearly all patients will experience mucosal candidiasis and up to 20% of patients will experience more difficult problems with esophagitis or fluconazole-resistant infection. Systemic infection with Cryptococcus neoformans, Histoplasma capsulatum, other endemic mycoses, or opportunistic molds including Aspergillus spp. and Mucor spp. are less common but more serious than candidiasis. Treatment with the new triazoles is effective for many cases but mortality and treatment failure remains common in cryptococcosis, more effective antifungal agents are needed. Although most patients do respond to therapy, relapse is common; suppressive therapy is required to prevent recurrence of systemic infection and in some cases of mucosal candidiasis. Studies in progress will determine the role of primary antifungal prophylaxis to prevent fungal infection in AIDS.