A Study to Demonstrate That Anti-HIV Drug Therapy Can be Stopped Without Causing Viral Resistance, and to Characterize Drug Elimination From the Body

Inclusion Criteria Patients may be eligible for this study if they: * Are at least 18 years old. * Are on EFV and at least 2 other anti-HIV drugs. * Are HIV-infected. * Have a CD4 cell count greater than 350 cells/mm3 within 21 days of study entry. * Have a viral load less than 50 copies/ml within 21 days of study entry. * Have an estimated creatinine clearance greater than 30 ml/minute within 21 days of study entry. * Have a negative pregnancy test if female. All patients able to have children must agree not to become pregnant or to impregnate or agree to use 2 reliable methods of contraception, including a barrier method. * Are planning to stop anti-HIV drugs as part of another study, not solely to participate in this study. * (This study has been changed. In an earlier version, EFV plus lamivudine plus zidovudine or stavudine was required.) Exclusion Criteria Patients may not be eligible for this study if they: * Had a serious illness and have not finished therapy for the illness or become stable on the therapy. * Abuse alcohol or drugs. * Have taken any nonnucleoside reverse transcriptase inhibitor other than EFV. * (This study has been changed. In an earlier version, patients were ineligible if they had taken certain anti-HIV agents or stopped treatment for more than 7 days in a row before the study.)