Twenty-two eyes of 19 patients with the acquired immunodeficiency syndrome who had pars plana vitrectomy and silicone-oil injection after retinal detachment caused by cytomegalovirus retinitis were studied. All patients but one were monitored until time of death. The postoperative survival time and the factors that predicted anatomic success (retinal attachment) and functional success (visual acuity) were analyzed. No intraoperative complications were encountered. The mean survival time after surgery was four months. Of all of the preoperative and intraoperative factors studied, only the duration of cytomegalovirus retinitis was predictive of survival (P less than .03). The anatomic success rate was 89.5% (17 of 19 patients). None of the factors showed a trend or statistical significance in relation to anatomic success. Fifteen of 19 patients (79%) had lost at least two lines of Snellen visual acuity at time of death. Vision declined in a bimodal pattern (within the first postoperative month and after four months postoperatively). The optic nerve was pink and well perfused preoperatively in 16 of 19 patients (81.8%), but optic-nerve atrophy was observed postoperatively in 18 of 19 patients (95.5%). There was a trend for functional success to be influenced by increased intraocular pressure and optic-nerve atrophy, although our sample size was too small for statistical significance.