['Metabolic syndrome has clinical implications for chronic liver disease, but the relationship between chronic hepatitis B and metabolic syndrome remains unclear. The aim of this study was to determine whether hepatitis B surface antigen (HBsAg) positivity is associated with metabolic syndrome.', 'Data were obtained from the Third Korean National Health and Nutrition Examination Survey (KNHANES). Participant sera were tested for HBsAg. Metabolic syndrome was defined according to the modified National Cholesterol Education Program Adult Treatment Panel III guidelines for Koreans.', 'Of the 5108 participants, 209 (4.1%) tested positive for HBsAg, and 1364 (26.7%) were diagnosed with metabolic syndrome. The prevalence of metabolic syndrome was 23.4% in HBsAg-positive men, 31.5% in HBsAg-negative men, 18.6% in HBsAg-positive women, and 23.7% in HBsAg-negative women. After adjusting for multiple factors, male participants who tested positive for serum HBsAg had an odds ratio of 0.612 (95% confidence interval [CI] 0.375-0.998) for metabolic syndrome and an odds ratio of 0.631 (95% CI 0.404-0.986) for elevated triglycerides. Women who tested positive for serum HBsAg had an odds ratio of 0.343 (95% CI 0.170-0.693) for elevated triglycerides.'] Is serum HBV surface antigen positivity associated with low prevalence of metabolic syndrome in Korean adult men?