Eleven years have elapsed since the hepatitis type C was first reported and treatment with interferon alone has resulted in about 30% recovery in man. In the case of heavy infection by HCV genotype 1b, 2a, interferon treatment has not been wholly satisfactory and treatment with long term combination of interferon and ribavirin appears to be most effective and a combination of interferon, ribavirin may become the mainstream of the treatment. A duration of one year appears to be most satisfactory. Even when this combination therapy is going, heavy infection by HCV genotype 1b recovery is about 50% and in order to prevent the occurrence of carcinoma, long term treatment with a small dose of interferon must be considered. New agent other than ribavirin must be developed.