To standardize diagnosis, treatment, and management of chronic hepatitis B, updated treatment guidelines in Japan have been formulated by a research team of the Japanese Ministry of Health, Labor and Welfare (MHLW)'s study project "Research on standardization of treatment for viral liver diseases including liver cirrhosis." The guidelines recommend first that chronic hepatitis B patients characterized by ALT levels of at least 31IU/l, with HBe antigen (HBeAg)-positive patients having HBV DNA levels of at least 5log copies/ml and HBeAg-negative patients with HBV DNA levels of at least 4log copies/ml, be targeted for treatment. Patients indicated for treatment intervention, for whom are suggested such basic treatments as entecavir therapy, long-term interferon (IFN) therapy, and sequential therapy, are divided into age groups comprising young patients (less than 35years of age) and middle-aged/elderly patients (35years and older), HBeAg-positive and HBe-negative patients, and patients with HBV DNA levels of at least 7log copies/ml and those of less than 7log copies/ml. As for switching to entecavir for chronic hepatitis B patients currently undergoing lamivudine therapy, the guidelines suggest specific therapies for different groups, dividing patients into those undergoing lamivudine therapy for less than 3years and those treated for 3years or longer, as well as those having HBV DNA levels of less than 1.8log copies/ml and those of 1.8log copies/ml or more. Formulated on the basis of consideration of chronic hepatitis B patient age, ALT level, HBeAg status, HBV DNA level, and liver disease severity, these guidelines are considered useful for the understanding and implementation of chronic hepatitis B infection diagnosis and treatment, which in recent years have advanced markedly and grown ever more diverse.