Chronic hepatitis B infection induces progressive liver disease. Before nucleos(t)ide analogs(NUCs) became established as a safe and effective treatment for hepatitis B,it was difficult to suppress the activity of the hepatitis B virus(HBV). Currently,many patients withhepatitis or cirrhosis associated with HBV are treated with NUCs for an extended period of time,and the effects,benefits,and limitations of these treatments have been apparent. This article reviews HBV-related cirrhosis,its natural course and survival,histological improvement after NUC treatments,treatment effects for decompensated cirrhosis,the incidence of hepatocellular carcinoma(HCC) after NUC treatments,and the efficacy of NUC treatments before and after the treatment of patients for HBV-related HCC. Of particular interest are the histological improvements,including regression of fibrosis,that have been achieved with NUC treatments. Liver function of patients with decompensated cirrhosis has significantly improved regardless of the type of NUC applied,and treatment with NUCs has reduced the incidence of HCC in cirrhotic patients. However,cirrhosis remains the strongest risk factor for HCC occurrence following NUC treatments,and the long-term cumulative incidence of HCC after NUC treatments remains high. When recurrence does occur,it is important to reconsider the treatment modality according to the degree of improved liver function that was achieved. Before nucleos (t) ide analogs (NUCs) established established as a safe and effective treatment for hepatitis B, it was difficult to suppress the activity of the hepatitis B virus (HBV). Currently, many patients with hepatitis or cirrhosis associated with HBV are treated with NUCs for an extended period of time, and the effects, benefits, and limitations of these treatments have been apparent. This article reviews HBV-related cirrhosis, its natural course and survival, histological improvement after NUC treatments, treatment effects for decompensated cirrhosis, the incidence of hepatocellular carcinoma (HCC) after NUC treatments, and the efficacy of NUC treatments before and after the treatment of patients for HBV-related HCC. Of particular interest are the histological improvements, including regression of fibrosis, that have been achieved with NUC treatments. Liver function of patients with decompensated cirrhosis has significantly improved r egardless of the type of NUC applied, and treatment with NUCs has reduced the incidence of HCC in cirrhotic patients. However, cirrhosis remains the strongest risk factor for HCC occurrence following NUC treatments, and the long-term cumulative incidence of HCC after N routine treatments when recurrence does occur, it is important to reconsider the treatment modality according to the degree of improved liver function that was achieved.