Although changing therapies is a common strategy in the treatment of HIV disease, guidelines are needed to help clinicians and patients decide when a change in antiretroviral therapy is indicated. The technology of measuring HIV RNA in plasma has been suggested as a tool for monitoring clinical drug efficacy. However, uncertainty remains about whether aggressive antiretroviral treatment to lower HIV RNA and maintain low levels for as long as possible will confer clinical benefit in comparison with management based on monitoring CD4 counts and HIV-related symptoms.