To investigate the association between calmodulin1 (CALM1) gene or estrogen receptor-alpha (ESR1) polymorphisms and double curve of adolescent idiopathic scoliosis (AIS).67 double curve patients (30 degrees T) and rs5871 locus in CALM1 gene, rs2234693 (PvuII) and rs9340799 (XbaI) in ESR1 gene analyzed sequence by ABI3730 genetic analyzer.There were 60 patients with Cobb angle > or = 40 degrees . According to the apical location of major curve, there were 40 thoracic curve patients. Furthermore, 1) there are statistical differences on the polymorphic distribution of ESR1 gene rs2234693 site between the double curve, Cobb angle > or = 40 degrees or thoracic curve patients and the controls, respectively (chi(2) = 6.081, 5.554, 6.1935; P = 0.014, 0.0128, 0.0184); 2) between the double curve cases and the controls, there is difference on the polymorphic distribution of rs12885713 site in CALM1 gene (chi(2) = 4.478; P = 0.034); 3) Between the thoracic curve patients and the controls, there is difference on the distribution of rs5871 allele polymorphism in CALM1 gene (chi(2) = 6.6061; P = 0.0102).Double curve patterns might be related to ESR1 gene rs2234693 (PvuII) site polymorphism. It is necessary to clarify the association between the polymorphisms of ESR1 gene and CALM1 gene and different subtypes of adolescent idiopathic scoliosis in the further study.