Objective To explore the potential estrogen-like activity of GH (growth hormone) gene in transgenic carp. Method Uterotropic assay was used. Nineteen-day-old immature female rats were randomly divided into 6 groups: using corn oil 5ml /(kg BW?d) in vehicle control group, parental carp meal 3 g/(kg BW?d) in counterpart control group, GH gene transgenic carp meal 3 g/(kg BW?d) in transgenic carp group, oral administration with 1μg /(kg BW?d) in oral low E₂ group, oral administration with E₂ 3μg/(kg BW?d) in oral high E₂ group, and hypodermic injection with E₂ 3μg /(kg BW?d) in hypoderm high E₂ group. All animal groups were given related test substances for 3 days (from the postnatal day 19 to day 21). The wet and dry weights of uterus were measured and the histopathological changes of uterus, ovary and vagina were examined by the end of the test. In addition, morphometric measurement of endometrial epithelium was conducted for quantitative comparison. Results Comparing with the vehicle control group, significant differences for wet and dry weights of uterus were observed in oral high E₂ group and hypoderm high E₂ group (P＜0.05), and no significant difference was observed in other groups. Conclusion No estrogenic effect of GH gene transgenic carp was shown in uterotropic assay.