Chronic hepatitis B is a common type of hepatitis B. Hepatitis B is characterized by a slow onset, with subclinical and chronic types being more common. Acute non-icteric HBsAg-positive patients are prone to chronic disease. The course of chronic hepatitis often exceeds half a year, and the disease can develop insidiously, often discovered during physical examinations. The symptoms vary, with recurrent attacks or prolonged illness. An estimated 5% to 10% of patients with acute hepatitis B develop into chronic hepatitis. The chronicity of acute hepatitis B depends mainly on the age of initial infection, immune status, and viral levels. Infections in infancy and childhood are prone to chronic disease. Patients using immunosuppressants and cytotoxic drugs, and patients with chronic renal failure on hemodialysis often lack obvious acute phase manifestations and have a protracted illness. Patients with very high serum levels of viral replication markers (HBeAg, HBV DNA) are more likely to develop chronic hepatitis.