Opportunistic fungal infections are commonly encountered in the acquired immunodeficiency syndrome (AIDS) patient population. Fungal infections in the patient infected with the human immunodeficiency virus (HIV) are a major cause of morbidity and mortality. The yeasts Candida and Cryptococcus neoformans, the dimorphic fungi Histoplasma capsulatum and Sporothrix schenckii, and the dermatophyte fungi are the most common pathogenic fungi in patients infected with HIV. The characteristics of these and other relevant mycotic pathogens, and their clinical presentation are discussed. Mycoses in the patient infected with HIV are often atypical, and can be masked by other infections. Cutaneous manifestations may provide valuable diagnostic clues. The clinician must maintain a high index of suspicion to establish an early diagnosis and rapidly institute therapy. Treatment may suppress rather than cure the mycosis, because host immunity in conjunction with antifungal agents is necessary to eliminate infection.