A lack of consensus exists with regard to the optimal positioning regimen for patients after macula-involving retinal detachment (RD) repair. To evaluate the effect of face-down positioning vs support-the-break positioning on retinal displacement and distortion after macula-involving RD repair. A prospective 6-month single-masked randomized clinical trial was conducted at a multicenter tertiary referral setting from May 16, 2016, to May 1, 2018. Inclusion criteria were fovea-involving rhegmatogenous RD; central visual loss within 14 days; patients undergoing primary vitrectomy and gas surgery, under local anesthetic; patients able to give written informed consent; and 18 years old and older. Analysis was conducted following a modified intention-to-treat principle, with patients experiencing a redetachment or failure to attach the macula being excluded from analysis. Participants were randomized 1:1 to receive face-down positioning or support-the-break positioning for a 24-hour period postoperatively. Positioning compliance was not monitored. The proportion of patients with retinal displacement on autofluorescence imaging at 6 months postoperatively. Secondary outcomes included proportion of patients with displacement at 2 months; amplitude of displacement at 2 and 6 months; corrected Early Treatment Diabetic Retinopathy Study visual acuity; objective Distortion Scores; and quality of life questionnaire scores at 6 months. Of the 262 randomized patients, 239 were analyzed (171 male [71.5%]; mean [SD] age, 60.8 [9.8] years). At 6 months, retinal displacement was detected in 42 of 100 (42%) in the face-down positioning group vs 58 of 103 (56%) in the support-the-break positioning group (odds ratio, 1.77; 95%CI, 1.01-3.11; P = .04). The degree of displacement was lower in the face-down group. Groups were similar in corrected visual acuity (face-down, 74 letters vs support-the-break, 75 letters), objective D Chart Distortion Scores (range: 0, no distortion to 41.6, severe distortion; with face-down at 4.5 vs support-the-break at 4.2), and quality of life scores (face-down 89.3 vs support-the-break 89.0) at 2 and 6 months. Retinal redetachment rate was similar in both groups (face-down group, 12.2% and support-the-break group, 13.7%). Retinal folds were less common in the face-down positioning group vs the support-the-break positioning group (5.3% vs 13.5%, respectively; odds ratio, 2.8; 95% CI, 1.2-7.4; P = .03). Binocular diplopia was more common in the support-the-break group compared with the face-down positioning group (7.6% vs 1.5%, respectively; odds ratio, 5.3; 95% CI, 1.3-24.6; P = .03). Amplitude of displacement was associated with worse visual acuity (r = -0.5; P < .001) and distortion (r = 0.28; P = .008). In this study, findings suggest that face-down positioning was associated with a reduction in the rate and amplitude of postoperative retinal displacement after macula-involving RD repair and with a reduction in binocular diplopia. No association was found with visual acuity or postoperative distortion. ClinicalTrials.gov Identifier: NCT02748538.