Objective To study the mechanisms of Jianfei Capsule on alimentary obesity rats at molecular level.Methods The level of Leptin mRNA in adipose tissue and neusopeptide Y （NPY） mRNA and UCP2 mRNA in hypothalamus of rats in medicine treatment and model control groups were observed by in situ hybridization. The content of Leptin and NPY in medicine and non-medicine treatment groups were detected by radio immunoassay.Results As compared with model control group

the level of Leptin in high and low dosage of Jianfei Capsule groups decreased

but there was no significant difference （P>0.05）; the level of NPY decreased but UCP2 mRNA increased significantly （P<0.01 or P<0.05）; the level of Leptin mRNA in adipose tissue and NPY mRNA in hypothalamus in high dosage of Jianfei Capsule group decreased significantly （P<0.01 or P<0.05）.Conclusion Jianfei Capsule can reduce weight of rats with alimentary obesity

which might be relevant to its regulating the expression of Leptin mRNA in adipose tissue and NPY mRNA and UCP2 mRNA in hypothalamus.