Patients begin study by initiating a HAART regimen of a minimum of 3 drugs, at least 1 of which must be a PI [AS PER AMENDMENT 2/27/01: or efavirenz (EFV)]. A variety of drug combinations are used; therefore, patients are grouped according to the classes of drugs in their respective regimen (e.g., 2 nucleoside reverse transcriptase inhibitors [NRTIs] plus 1 PI; 2 NRTIs plus 2 PIs; 1 or 2 NRTIs plus 1 PI plus 1 nonnucleoside reverse transcriptase inhibitor [NNRTI] [AS PER AMENDMENT 2/27/01: ; and 2 NRTIs plus EFV]). At the time of HAART initiation, patients undergo immunologic and virologic assessments in order to determine baseline values. Then, to determine the virologic success or failure of HAART, HIV-1 RNA measurements are taken and compared to initial baseline values. Virologic success equals undetectable HIV-1 RNA at Week 12 [AS PER AMENDMENT 2/27/01: and confirmed at Week 16] or a significant (greater than 1 log) decrease in HIV-1 RNA from baseline to Week 12 [AS PER AMENDMENT 2/27/01: and confirmed undetectable HIV-1 RNA before the next scheduled visit (Week 24)]. Patients are followed for a minimum of 3 years of maintained viral suppression or until they have demonstrated virologic failure. From these values, any correlation that may exist between HIV-1 RNA values and HAART can be deduced. Patients with virologic failure on the initial HAART regimen may be allowed to change to a second HAART regimen. [AS PER AMENDMENT 2/27/01: Patients with virologic success on the second HAART regimen are followed for a minimum of 3 years.] Patients with virologic failure on the second HAART regimen or who voluntarily discontinue HAART are followed using an abbreviated schedule for 3 years.