Abstract： Objective To evaluate the expression of TGF-β1 and TGF-βrⅢ in genital tubercle (GT) of hypospadiac male rats induced by maternal exposure to DBP. Methods Twenty timed preg-nant rats were randomly divided into 2 groups and were given Di-n-butylphthalate (DBP) by gastric in-tubation at a dose of 0 or 750 mg/kg from gestation day(GD) 14 to GD18. On postnatal day (PND 1), live pups were counted and male pups were examined for hypospadias. On PNDT, The anogenital dis-tance (AGD) and body weight of male pups were measured. The gross image and the histologic chan-ges of hypospadiac genitalia were checked. Meanwhile, real-time quantitative PCR were used to quanti-fy mRNA expression of TGF-β1 and TGF-β rⅢ in GT of hypospadiac male rats. Results The number of live pups in the DBP treating group was significantly decreased and the incidence of hypospadias was 43. 750%. The body weight and the AGD of hypospadiac male rats were significantly decreased on PND7. The general and the pathological changes of hypospadiac genitalia were also observed. Moreo-ver,significantly decreased gene expressions of TGF-β1 and TGF-βr Ⅲ were found. Conclusions There were obviously toxic effects of DBP to the pregnant rats. The down-regulation expression of TGF-β signaling molecules might lead to the development of hypospadias induced by maternal exposure to DBP.