The incidence and prevalence of HIV infection in older adults is rising, with disproportionate increases in women and minorities. Compared with younger adults, older patients who have HIV often are diagnosed later in the course of the disease and may have an accelerated decline in immune function. Although the prognosis for older adults has improved with the initiation of highly active antiretroviral therapy, there remains a higher risk for comorbid illness. Additional efforts to diagnose and prevent HIV infection in this older age group are necessary to decrease the transmission of HIV and to reduce the morbidity and mortality associated with this infection.