Background & Objectives: To determine the prevalence of HBV infection in the Golestan Province (southeastern part of the Caspian littoral, Iran). Methods: A single cluster study was conducted in 2005, based on a sample of households, representative of the population aged 25-65 years in Golestan. All participants were invited for face-to-face interviews to gather demographic data. Blood samples were drawn and analyzed for serum markers of HBV infection such as HBsAg and HBcAb by the ELISA method. Factors associated with hepatitis B seroprevalence were analyzed using SPSS13 and STATA /8. Results: A total of 1850 subjects were screened. The age- & sex-standardized prevalence for HBsAg positivity was 9.7% (95%CI=0.07-0.11). Rates were higher in males than in females (10.8% vs. 8.6%) (OR=1.28; 95% CI=0.9-1.7). HBV seroprevalence in unmarried individuals was significantly higher than in those who were married (OR=2.13; 95%CI=1.29-3.5). HBsAg(+) status was more frequent in urban areas (OR=1.46; 95% CI=0.9-2.3). Thirty-six percent of population was HBcAb positive. HBcAb(+) prevalence was significantly higher in females (OR=1.46; 95% CI=1.19-1.8) and married people (OR=1.58; 95%CI=1.02-2.45), and also in urban areas (OR=1.34; 95% CI=1.09-1.6). Conclusions: This study shows that the prevalence of HBsAg(+) status in the Iranian province of Golestan is at a level regarded as "high" by the World Health Organization. It is higher than reported by pervious studies in Iran so it is important- especially for health providers and policy makers- to recognize risk factors and design appropriate prevention programs.