The author studied the sero-immunological characters of the infectious hepatitis virus isolated by the chik-embryo technic. The results are briefly summarized as follows: 1) In some cases of the neutralization test and Absaettigungsversuch, with young hamsters. a pretty high degree of noutralizatien could be observed, but no definite result could be obtained. 2) With the use of chick-embryos, the neutralization could be well established between the isolated virus and convalescent sera; this fact indicates that the isolated virus is from the patients of infectious hepatitis. 3) The intracutaneous reaction with the antigen prepared from the isolated virus-infected animal organs showed a unequivocal difference to the control. Though further studies are needed, this fact suggests the existence of the relationship between the isolated virus and the infectious hepatitis.