The etiology of Perthes' disease is unclear. Recent reports have suggested that inheritable thrombophilic disorders may be one of its pathogenetic causes. The G20210A prothrombin gene, factor V Leiden, and MTHFR C677T mutations have been identified as predisposing genetic factors for thrombosis. Ninety children diagnosed with Perthes' disease were studied. A family history of thrombosis and any other personal thromboembolic events were researched. PCR and endonuclease digestion were used to analyze factor V Leiden, prothrombin G20210A, and MTHFR C677T. Two hundred healthy donors were included as a control group. No patient had a family or personal history of early thrombotic events. Four children with Perthes' disease (4.4%) were heterozygous for G20210A polymorphism compared with controls (odds ratio: 2.07; 95% confidence interval: 0.40-8.46). No association between factor V Leiden and Perthes' disease was observed. Three patients (3.33%) were heterozygous for factor V Leiden (odds ratio: 1.36; 95% confidence interval: 0.32-5.84). The prevalence of different genotypes of C677T MTHFR did not show statistical differences compared with controls. Eleven patients were homozygous for this polymorphism (odds ratio: 1.02; 95% confidence interval: 0.42-2.44). This study does not support the screening of this group of polymorphism in patients with Perthes' disease.