This is a parallel, time-lagged, 2-stage, multiple-dose, 24-week study in HIV-1 seropositive patients. In the 3-week, randomized, double-blind phase of Stage A, patients receive either indinavir plus nelfinavir (Group A1: 9 patients) or indinavir placebo plus nelfinavir placebo (Group A2: 3 patients) for the first week. In Week 2, patients in Group A1 have the nelfinavir dose increased. This dose escalation for nelfinavir is contingent upon the patient having completed 1 week of the study drugs without experiencing Grade 3 or worse toxicity and/or serious drug-related adverse events. Patients in Group A2 continue to receive placebo until Week 3, at which time they receive indinavir plus nelfinavir (initial dose), while patients in Group A1 continue with indinavir plus nelfinavir (escalated dose). At Week 4 all patients in Stage A (including those originally assigned to receive placebo) receive open-label indinavir plus nelfinavir (escalated dose) for the remainder of the 24 weeks.