Hong tang 1 ✉ the correlation between hepatitis B virus (HBV) infection and metabolic syndrome (MetS) remains to be clarified. In this study, we explored this association in a large population in Southwest China. This was a cross-sectional study, with pooled adult health data. Multivariate logistic regression analysis, controlling for age, sex, HBV status, alanine aminotransferase, and fatty liver, was used to identify predictor(s) of MetS. Of the 96,175 participants, positive HBV was identified in 7984 (8.30%) and MetS in 12,092 (12.57%). The MetS prevalence was lower among HBV positive than negative individuals (11.64% versus 12.66%, P < 0.001). The adjusted odds (aOR) of positive HBV among individuals with MetS was 0.841 (95% confidence interval (CI), 0.771-0.916) in men and 0.834 (95% CI, 0.672-0.925) in women. Elevated triglyceride level, a component of MetS, was inversely associated with HBV status in both men and women: aOR, 0.551 (95% CI, 0.514-0.590) and 0.683 (95% CI, 0.605-0.769), respectively. Among HBV positive individuals, liver cirrhosis was more common among those with than without MetS (4.83% versus 2.93%, respectively; P = 0.002). HBsAg-seropositive are inversely associated with MetS, especially elevated triglycerides. Liver cirrhosis was more common among HBV infection patients with MetS. Chronic hepatitis B virus (HBV) infection is a major public health issue 1. HBV infection is not only the cause of acute and chronic hepatitis, but is also one of the key etiological factors of liver cirrhosis and hepatocellular carcinoma (HCC). In 2015, it was estimated that 257 million people, 3.5% of the world's population, were living with a chronic HBV infection 2. In China, a HBV-endemic region, the prevalence of HBV infection for population among individual 1 to 59 years of age is approximately 7.18%, with an estimated 93 million patients individuals in China living with a chronic HBV infection 3. Although the health morbidities of chronic HBV infection are decreasing, these remain a tremendous healthcare burden in China. Considering that the liver plays a key role in glucose homeostasis and lipid metabolism, the possible association between liver disease and diabetes mellitus or metabolic syndrome (MetS) has been a topic of healthcare research interest. MetS refers to diseases caused by metabolic disturbances, such as increased waist circumference, hyperglycemia, elevated blood pressure (BP), and dyslipidemia. MetS affects approximately one-fifth in China, reflecting the increasing prevalence of obesity 4,5. MetS is characterized by dyslipidemia and glucose metabolism disorders, both of which are influenced by hepatic function. In fact, an association between MetS and non-alcoholic fatty liver disease (NAFLD), chronic hepatitis C (CHC) and HCC has previously been demonstrated 6,7. Additionally, NAFLD is considered as the hepatic manifestation of MetS 8. It is also now widely confirmed that chronic hepatitis C virus infection may increase the risk of insulin resistance and type 2 diabetes 9. MetS is als...