Patients must be on a stable HAART -regimen for greater than or equal to 3 months prior to entry. The HAART regimen must consist of at least 3 drugs and include at least 2 classes of drugs. Individuals with sustained viral suppression on a regimen of abacavir plus 2 other nucleoside reverse transcriptase inhibitors will be eligible at the discretion of the investigators. The use of hydroxyurea will not be permitted.