Total hip arthroplasty can now be performed in adolescents and even children whose growth is not yet completed. The main objective of the procedure is to enable these patients to enjoy as normal a life style as possible. However, extreme caution is needed when selecting patients. Technical requirements aimed at preserving bone and muscle and at delaying prosthesis wear and loosening are discussed. The authors recommend use of a cemented implant with a 22.2 mm head and a metal-polyethylene friction couple, inserted by the lateral route after reclining the gluteal muscles.