Purpose: To analyze the clinical characteristics and relevant prognostic factors of vitrectomy for retinal detachment (RD) secondary to cytomegalovirus retinitis (CMVR) in patients with acquired immune deficiency syndrome (AIDS). Methods: This study involved 39 eyes that underwent vitrectomy. Best-corrected visual acuity (BCVA), CD4(+)cell counts, retinal attachment rate, and prognostic factors were assessed 1, 3, and 6 months postoperatively. Results: The rate of retinal attachment at 1 month (87.2%) was higher than at 3 (82.1%) and 6 (71.8%) months. Factors significantly related with recurrent RD at 6 months were CD4(+)cell count <50 cell/mu L (p= .000) and relaxed retinotomy (p= .002). Factors significantly related with the visual (<= logMAR1.0) prognosis at 6 months include band keratopathy (p= .015) and macular involvement by the RD (p= .012). Conclusion: CD4(+)cell counts <50 cell/mu L and relaxed retinotomy are associated with worse prognosis, while band keratopathy and macular involvement by the RD are related to poorer vision.