Abstract Background and objectives: Herpes simplex virus type two (HSV-2) infections are mostly considered as a sexually transmitted disease. It causes genital herpes, newborn herpes non-pyrogenic meningitis and may act as an underlying factor for HIV infection. This study was conducted to determine the sero-epidemiologic prevalence of herpes simplex virus type two in cases referred to ten clinical laboratories of Gorgan. Materials and methods: This cross- sectional study was performed on blood Samples of 406 randomly selected Clients. These samples were analyzed for Anti HSV-2 using Specific enzyme-Linked immunoassays (ELIZA) Results: Four point nine percent of all subjects have anti HSV-2. There is Significant difference between sero-positive HSV-2 and factors such as age and Marital Status (P<0.05). Conclusion: HIV is progressively increased and HSV-2 infection is one of the major risk factors for HIV therefore, decreasing the prevalence of HSV-2 infections may Leads to the reduction of HIV prevalence. Key word: HSV-2, Antibody, Gorgan, Sero-epidemiology.