Objectives: We evaluated the long-term radiological outcomes of the patients with Perthes disease who were conservatively treated with brace. Patients and methods: Thirty-three hips of 27 skeletally mature patients (21 males, 6 females; mean age 25.2±3.4 years; range 20 to 32 years) treated with modified Thomas splint were included in this study. The results were evaluated according to the Stulberg classification. Results: The mean age of the patients was 6.3±2.2 (range 3-12) years at the onset of the disease and the mean follow-up was 18.6±3.2 (range 7.2-24.1) years. According to onset of the disease, good results were obtained for the patients who were less than six-years-old as 77.7%, between 6-9 years old as 84.2%, after nine years old as 40%. However, 100% of the Herring group A hips, 79.2% of the group B hips and 50% of the group C hips were healed with Stulberg class I or II results. Conclusion: We obtained satisfactory results after conservative treatment with Thomas splint in patients who were between 6-9 years old at onset of the disease with Herring group B involvement. It is hard to say whether the good results were stemmed from having good prognosis of these patients, or stemmed from positive effect of using brace on treatment.