All patients receive L-756423 plus indinavir plus two licensed nucleoside reverse transcriptase inhibitors (NRTIs), at least one to which the patient is naive. Patients remain on the drug regimen for 12 weeks (with possible extension to 16 weeks). Patients are evaluated with physical examinations and laboratory tests for blood and urine at Weeks 1, 2, 4, 6, 8, and 12 and two weeks post study. Plasma viral RNA is measured at Weeks 1, 2, 4, 6, 8, and 12. CD4 cell counts are measured at Weeks 2,4,8, and 12.