Abstract: Objectives In order to know the changes of HBV DNA in patients with chronic hepatitis B. Methods To observe and compare the model for end-stage liver disease（MELD） scores and HBV DNA loads in 51 cases with acute-on-chronic liver failure and 56 with chronic hepatitis B of severe degree. Results MELD scores in peak and convalescent stages in patients with acute-on-chronic liver failure were 20.5±4.4 and 12.2±6.1,and HBV DNA loads were 6.2±1.5 log10 copies/ml and 4.5±1.5 log10 copies/ml,respectively;MELD scores in peak and convalescent stages in patients with chronic hepatitis B were 11.9±3.2 and 6.4±3.1,and HBV DNA loads were 6.5±1.5 log10 copies/ml and 4.9±1.8 log10 copies/ml,respectively（t=6.692~13.215,all P<0.000）. Conclusion No matter in patients with acute-on-chronic liver failure or chronic hepatitis B,their serum HBV DNA loads has spontaneously decreased in convalescent stages.

Key words: Hepatitis B, Model for end-stage liver disease, HBV DNA