The National Institutes of Health, the HIV Medicine Association of the Infectious Diseases Society of America, and CDC have developed guidelines for treatment of opportunistic infections (OIs) among adults and adolescents infected with human immunodeficiency virus (HIV). These guidelines are intended for clinicians and other health-care providers who care for HIV-infected adults and adolescents, including pregnant women; they complement companion guidelines for treatment of OIs among HIV-infected children and previously published guidelines for prevention of OIs in these populations. They include evidence-based guidelines for treatment of 28 OIs caused by protozoa, bacteria, fungi, and viruses, including certain OIs endemic in other parts of the world but that might be observed in patients in the United States. Each OI section includes information on epidemiology, clinical manifestations, diagnosis, treatment recommendations, monitoring and adverse events, management of treatment failure, prevention of recurrence, and special considerations in pregnancy. Tables address drugs and doses, drug toxicities, drug interactions, adjustment of drug doses in persons with reduced renal function, and data about use of drugs in pregnant women.