Recently γ-globulin is widely used for the prevention of infectious hepatitis in the field of clinical medicine, but its conclusive effect is still in question. In the prcsent part, the author studied what changes the administration of γ-globulin produced in the infectious aspect of hepatitis. The γ-globulin obtained from the healthy men and the one from the convalescents of hepatitis were used, and the infectious aspect was judged by the pathological findings in the mouse. It is noteworthy that the γ-globulin of convalescent sera showed a little noticeable preventive effect, though not a remarkable one. Consequently, it is inferred that more reliable effect will be obtained by using the γ-globulin containing a sufficient amount of antibody, and also by employing other various methods.