The effectiveness of psoas and adductor tenotomies for the prevention of hip dislocation was investigated in 40 hips of 24 total-body-involved children. Age at operation ranged from 1.6 to 10 years. Results were evaluated by the Reimers migration percentage (MP). Average follow-up was 3 years. An overall good result was observed in 67% of cases. Results were correlated with age and MP at operation. Successful results were obtained in 90% of patients under age 4 who had an MP <33%. Preventive surgery should be performed at 2 or 3 years of age, before the onset of hip dysplasia.