Hepatitis B virus (HBV) infection is a serious global health problem, with 2 billion people infected worldwide, and 350 million suffering from chronic HBV infection. Being the 10th leading cause of death worldwide, HBV infections result in 0.5 to 1.2 million deaths per year caused by chronic hepatitis, cirrhosis, and hepatocellular carcinoma. Besides, hepatitis B is a major health problem in Egypt. It was reported that HBV was more prevalent in Upper Egypt (11.7) than in Lower Egypt (8.8). The aim of the present work is to reveal the prevalence of HBV worldwide and in Egypt and to discuss updated clinical issues in the diagnosis and modern modalities of treatment. It was concluded that hopefully, the advent of universal infant vaccination, treatment of all forms of chronic HBV disease, and new screening methods, as well as treatment modalities for HBV induced cirrhosis and liver cancer in the next decade, will enable us to markedly decrease the incidence and prevalence of this worldwide endemic disease.