The purpose of this study was to evaluate the magnetic resonance imaging (MRI) appearance of the hip capsule in patients with femoroacetabular impingement (FAI) undergoing hip arthroscopy with capsular repair versus non-repair. A multicenter clinical trial was performed with 31 patients (49 hips) undergoing hip arthroscopy for treatment of FAI. A small- to moderate-sized interportal capsulotomy was performed. Each hip was randomized to capsular repair versus non-repair of the interportal capsulotomy. MRI was performed at 6 and 24 weeks postoperatively and was analyzed by two musculoskeletal radiologists. Patients and the radiologists were blinded to the treatment applied. Capsular defect size and capsule thickness were recorded on each scan. Mean patient age was 31.4 years. Capsular repair was performed in 23 (46.9%) hips. Mean capsulotomy length was 35 mm at Center X and 23 mm at Center Y. At 6 weeks postoperatively, a healed hip capsule (with no apparent capsulotomy defect) was observed in 10 (43.4%) hips that underwent capsular repair and 4 (15.4%) hips that did not undergo capsular repair (P = 0.13). At 24 weeks postoperatively, 25/30 hips (83.3%) achieved complete closure of the capsulotomy defect, with no significant difference between treatment groups. Repair of an interportal capsulotomy following hip arthroscopy for FAI results in a non-significantly higher percentage of healed hip capsules at 6 weeks postoperatively compared with leaving the capsule unrepaired, though the difference normalizes by 24-week follow-up. Repair of a small- to moderate-sized interportal capsulotomy does not provide a radiographic advantage following hip arthroscopy for FAI.