Purpose. To investigate the effect of soft tissue release (STR) and the length of postoperative immobilisation on the long term outcomes of closed reduction (CR) of the hip for developmental dysplasia of the hip. Materials. 77 hips (72 patients) who had undergone closed reduction (CR) between 1977-2005 were studied retrospectively to review their outcome (Severin grade), identify the reasons for failure and to assess factors associated with residual dysplasia. Particular attention was paid to the use of a STR at the time of CR (to improve initial hip stability) and the duration of postoperative immobilisation. Results. The mean age at CR was 10.5 months (5-24months) and mean follow up 97 months. A STR (adductor ± psoas tenotomies) was performed in 65%. Post-operative immobilisation time varied between 3-12 months (mean 6.3 months). 6 hips (all Tonnis grade 3) failed CR within 2-6 weeks. In the remaining 49 hips, 85% were Severin Grade 1 at age 5yrs. Acetabular index (AI) decreased in all patients over time: 80% hips had an AI <20. 0. at age 5yrs. Neither a STR, nor the time of post-operative immobilisation conferred any additional benefit on the final AI. 2/55 hips required a pelvic osteotomy for residual dysplasia. This was not related to initial Tonnis grade, age at reduction or use of STR. Conclusion. A STR is often required for initial hip stability. Once a stable hip is achieved, an excellent long term outcome from CR in infants <24months old can be expected with remodelling of the acetabular dysplasia in ≥95%. Significance. Hip stability is the key to a good outcome. The optimal length of post-operative bracing has not been determined from this study but 3-6months immobilisation of the stable hip is adequate