A Comparison of Two Tests for Anti-HIV Drug Resistance

Inclusion Criteria Patients may be eligible for this study if they: * Are HIV-positive. * Have failed 2 to 4 anti-HIV regimens containing 3 or more combinations of drugs. A patient has failed his/her current regimen if he/she has, within 30 days of study entry, either a viral load (level of HIV in the blood) of at least 10,000 copies/ml or 2 tests which show a viral load between 1,000 and 10,000 copies/ml. * Have taken 3 or more anti-HIV drugs for 8 or more weeks before the study. * Are at least 14 years old. * Have consent of parent or guardian if less than 18 years old. Exclusion Criteria Patients will not be eligible for this study if they: * Have failed only 1 anti-HIV drug combination. * Have failed 5 or more anti-HIV drug combinations, each containing 3 to 5 drugs. * Have had and received the results of prior resistance tests. * Have had treatment with a combination of 6 or more anti-HIV drugs. * Have problems absorbing food in the intestine. * Have had HIV vaccines. * Have taken drugs that affect the immune system or investigational drugs. * Are taking medications not allowed with protease inhibitors (PIs) if PIs would be part of their anti-HIV treatment during the study. * Have failed anti-HIV therapy due to nonadherence to medication.