All patients will receive open label induction therapy with zidovudine (ZDV), lamivudine (3TC) and indinavir (IDV) for 6 months. Following the 6 month induction phase, patients with undetectable plasma HIV RNA at weeks 16, 20 and 24 will enter the maintenance phase [blinded maintenance phase AS PER AMENDMENT 09/19/97] and be randomized to one of three maintenance regimens, i.e., either continued ZDV/3TC/IDV (control), or ZDV/3TC/IDV placebo or ZDV placebo/3TC placebo/IDV. Prior to randomization, patients are stratified according to entry HIV RNA level (greater than or equal to 30,000 or less than 30,000 copies/ml) and by prior ZDV therapy (at least 7 days or less than 7 days). After 12 months [AS PER AMENDMENT 09/19/97: 18 months] of maintenance therapy, treatment will be withdrawn at 6-month intervals in randomly-selected patients who have achieved undetectable HIV RNA. AS PER 09/19/97 AMENDMENT: After 18 months of blinded maintenance therapy, treatment is unblinded for patients whose HIV RNA levels remain detectable. Such patients receive optimal therapy, either continuing the protocol regimen or initiating alternative therapy.