HIV/AIDS has the unfortunate distinction of being one of the most devastating epidemics of the twentieth century. By the end of June, 1999, 420,201 deaths in persons with AIDS had been reported in the United States. While HIV/AIDS patients are currently living longer as a result of more effective and complex treatments, no vaccination or cure has yet been discovered. Over the years, the HIV/AIDS epidemic has become multifactorial and currently affects several different special population groups. Individuals who are at high risk for becoming infected with HIV or who already suffer from HIV/AIDS can benefit greatly from the interventions of psychiatrists or other mental health professionals. It is important that psychiatrists collaborate very closely with infectious disease specialists in the management of HIV/AIDS and its psychological sequelae. The authors describe the psychiatric conditions that most often occur in association with HIV/AIDS: mood disorders, anxiety disorders, substance-related disorders, psychotic disorders, insomnia and sleep disorders, delirium, dementia, and pain syndromes. We present guidelines for diagnosis and psychopharmacological and psychotherapeutic treatment of these disorders in patients with HIV/AIDS. The article concludes with a discussion of prevention strategies that can be used in a mental health treatment setting and special issues related to treating HIV/AIDS in certain special population groups.