The aim of this study was to evaluate the radiographic correction and the complications in Southwick osteotomy for slipped capital femoral epiphysis (SCFE) on the basis of radiographic evaluation. We retrospectively analyzed the charts of 37 patients with chronic, unilateral, moderate, or severe SCFE, who underwent the procedure, verifying Southwick angles, articulotrochanteric distance, and the articular narrowing on preoperative, postoperative periods, and in the last follow-up evaluation, using the contralateral, healthy hip, for comparison. Southwick’s angle changed from 117.8 to 147.3° on average (front) and from 56.9 to 19.1° (Lauenstein view). Articulotrochanteric distance changed from 11.3 to 24.1 mm (normal distance 22.1 mm). Joint space changed from 4.3 mm preoperatively to 3.84 mm. Chondrolysis was diagnosed in five cases before and eight cases after surgery. There was no case of avascular necrosis. Southwick osteotomy effectively corrected SCFE deformity. There was a tendency toward excessive valgism.