This is very interesting for the orthopaedic community at large, especially for registrars. It would seem that the days of the controversies surrounding the pinning of the contralateral normal hip in slipped capital femoral epiphysis are numbered. The aim of the study was to identify the prevalence of chondrolysis, osteonecrosis and the degree of slip in contralateral hips with subsequent slipped capital femoral epiphysis. The authors demonstrated that the complications associated with a subsequent contralateral slip were greater than the risk of prophylactic pinning of the normal hip. In this retrospective study the incidence of a subsequent slip following pinning of the primary slip was 36%. Current literature reports a range of between 25% and 40%. The authors reviewed 227 patients operated between 1993 and 2003 at a single hospital. The average follow-up was 24 months or until skeletal maturity. A total of 82 patients had subsequent slips.