Objective To detect the effect of leptin on proliferation and c.Myc mRNA expression of human colon carcinoma HT-29 cell line and investigate the role of Leptin in the development of the HT-29 cell line.Methods Human colon carcinoma HT-29 cell line was cultured in vitro.After treatment with various concentration of Leptin for 72h.MTr was used to detect the proliferative and inhibitive status.And c-myc mRNA-expression Was detected by RT-PCR.Results After treatment with various concentration of Leptin.The cell pmlifemtion and c-myc mRNA expression Wag obviously promoted,compared with the control group.The effect wag in a time-dose-dependent manner within a certain range.Conclusion Leptin can improve cell proliferation and c-myc gene expression level in HT-29 cell line.Promoting the c-myc gene expression level may be one of the reasons that Leptin improves the proliferation of the human colon carcinoma HT-29 cell line.