Hepatitis A virus (HAV) is a single-stranded ribonucleic acid virus classified as a picornovirus. The distribution of the virus is worldwide although the incidence of HAV disease is higher in less developed areas and has been decreasing in the United States. Hepatitis B virus (HBV) is a deoxyribonucleic acid virus of the Hepadnaviridiae family. There are a number of ways to categorize viruses that cause hepatitis in children. Effective prevention in the form of vaccination is available, and infection can be prevented even in infants born to mothers with known active HBV disease, by administration of hepatitis B immune globulin followed by vaccination. Definitive diagnosis of Cytomegalovirus as a cause of hepatitis is problematic because of the ubiquity of the virus, the frequency of asymptomatic infections, and possible concomitant infection with other organisms. Treatments are available for many types of viral hepatitis and medical science is on the threshold of introducing more and better treatments.