Serum hepatitis B surface antigen (HBsAg) level has been developed as an important marker to predict treatment outcome recent years. The authors aimed to identify the correlation between quantitative HBsAg and hepatitis B virus (HBV) DNA level in chronic hepatitis B (CHB) patients and explore whether quantitative HBsAg can be used as a surrogate marker of serum HBV DNA for CHB patients. One hundred seventy-three patients were included in this study. Patients were divided into two groups: Hepatitis B e antigen (HBeAg) positive and negative patients. There was a positive correlation between quantitative HBsAg and HBV DNA level in HBeAg positive patients (r = 0.509, P < 0.001) and poor correlation in HBeAg negative patients (r = 0.176, P = 0.096). Interestingly, completely no correlation (r = -0.01, P = 0.994) was found in younger HBeAg negative patients (<40 years old), whereas in older HBeAg negative patients (>40 years old) there is a positive correlation (r = 0.448, P = 0.003). Mean HBsAg titer and Alanine aminotransferase (ALT) level were significantly higher in HBeAg positive group (3.81 log10 IU/mL; 105 IU/mL) than in negative group (2.85 log10 IU/mL; 32 IU/mL) (P < 0.001). We concluded that quantitative HBsAg could reflect HBV DNA level in HBeAg positive patients, but could not surrogate for HBV DNA level in HBeAg negative patients. Our study improves understanding of the relationship between HBsAg titers and HBV DNA levels in CHB patient and may have implications for future treatment algorithms evaluating the HBsAg titers in both HBeAg positive and negative patients.