The Authors have developed a work of meta-analysis on the employment of IFN in the virus-correlated chronic hepatitis. They have examined World literature on: virus causing chronic hepatitis, type and duration of the treatment, criteria in the choice of the observed patients, clinical effects, effects on the virus, effects on the isto-pathologic situation. Have been considered the useful actions at the end of the treatment and in the follow-ups, so to evaluate the permanence of favourable effects. Have been also reminded the main collateral effects, even about frequency and intensity, as the various Authors relate. There are quite clear data indicating: efficacy in B-correlated chronic hepatitis greater than in C-correlated ones, greater efficacy in the treatments with Interferon with duration of more then 6 months in chronic hepatitis C. Doses greater than those generally employed appear not to give better results. The Authors moreover show the results of a clinical survey they made on patients with chronic hepatitis HBsAg+/HBeAg+ (treated with IFN-alpha 2r 5 MU t.i.w. for six months) and chronic hepatitis anti-HCV+ (treated with IFN-alpha 2r 3 MU t.i.w. for six months). The results confirm the efficacy of IFN in B-correlated chronic hepatitis (50% of sustained response) and its scarce efficacy in C-correlated chronic hepatitis for treatment shorter than 12 months (9.1% of sustained response).