Candida krusei is an emerging pathogen, both in HIV negative immunocompromised patients and in HIV seropositive patients. Its onset appears to be due, at least in part, to the use of fluconazole. In HIV positive patients, a long term prophylactic use of fluconazole may select some less pathogenic Candida species, as C. krusei, that may determine persistent oral candidiasis and emerge as systemic pathogen. Itraconazole appears efficacious in treating AIDS-associated C. krusei infections.