Knowledge of the etiologies and pathogenesis of viral hepatitis has exploded in the last two decades. Accurate serologic methods for identification of the causative agents have lead to an understanding of the importance of viral hepatitis in the pathogenesis of acute and chronic hepatitis, cirrhosis, and hepatocellular carcinoma. Although treatment of infection remains a challenge, accurate methods of diagnosis and prevention of infection are now at the physician's disposal. Successful control of these debilitating infections will depend upon the proper utilization of existing methods of prophylaxis.