Objective:To observe the effect of viral interleukin-6(vIL-6) on the expression of DNA methyltransferase 1(DNMT1). Methods:The eukaryotic expression plasmid carrying vIL-6 gene was transferred into 293T cells. The expression of DNMT1 was examined by quantitative RT-PCR and Western blot. DNMT1 activity was analyzed by colorimetry. Results:Quantitative RT-PCR and Western blot demonstrated that vIL-6 increased the expression of DNMT1. Furthermore,vIL-6 upregulated the activity of DNMT1. Conclusion:vIL-6 can induce the expression of DNMT1. It may be one of the molecular mechanisms of Kaposi＇s sarcoma associated herpesvirus(KSHV)-induced DNA methylation abnormalities and oncogenesis.