The author studied clinical significance of auto-liver-antibody in liver diseases and obtained the following results. 1. Auto-iiver-antibody in liver diseases shows decidedly stronger pesitive reaction than in other diseases, and in addition, it presents a higher titer of the antibody. Especially in the liver disease other than infectious hepatitis such as in liver cirrhosis it may be emphasized that the antibody titer is high. 2. Auto-liver-antibody presents a close correlation with the liver functions and liver autopsy picture. 3. Auto-liver-antibody is quite useful for differential diagnosis and prognosis of liver diseases. 4. The mice previously sensitized wth homologous-liver-antigen or by albumin of eggwhite and attacked by Ectromelia virus are clearly at more disadvantage for the infection than in the case of non-sensitized mice. However, the difference between the two groups is not so distinct and the existence of liver-damaging action by the homologous- and auto-liver-antibodies can not be decided definitely.