[Objective] To explore the polymorphism of the 3′ flank region of equine IGF-Ⅰ gene. [Method] The 3′ flank region sequences of IGF-Ⅰ gene were amplified from genomic DNA of 270 horses, which included 4 types of Mongolian horse, Sanhe horse and Thoroughbred, and then analyzed by PCR-SSCP. [Result] Three genotypes (AA, BB and AB) were detected by PCR-SSCP and the distribution of genotypes of all research objects except Xinihe horse and Baerhu horse were in line with the "Hardy-Weinberg Law". [Conclusion] There was a polymorphic locus in the 3′ flank region of IGF-Ⅰ gene, which might affect the equine growth and development mechanism. The study is of important theoretical and practical significance to improve the performance and to develop equine industry.
