Worldside viral hepatitis is still recognized as a major problem particularly in developing countries. During the past two decades there has been important progress in the field of viral hepatitis; the adaptation of molecular biology techniques to viral hepatitis has proven to be of great utility in the diagnosis of 'classical' hepatitis viruses, in monitoring during treatment, and also in learning more about the 'new' viruses. Here, the progress and pitfalls of serologic and molecular diagnosis techniques for viral hepatitis, unusual profiles and benefits of quantitative DNA/RNA tests will be discussed.