The treatment of chronic viral hepatitis with Interferon has been introduced in clinical practice over the past decade an represents an important step in the management of those diseases. The data existing in literature are conflicting about the dose and period of treatment with Interferon, many treatment schedules being proposed. There are also a lot of markers used or proposed to be used to determine the response to treatment, their predicting efficacy being largely studied. The response to alpha-Interferon in a standard 6 month regimen in chronic hepatitis B, chronic hepatitis C and chronic hepatitis B and C is studied; alanine-aminotransferase (ALAT) and aspartate-aminotransferase (ASAT) are the markers used to determine the response to treatment.