A preliminary study was made on the experimental serum anaphylaxis and the followings were observed. The γ-globulin was decreased by shock, but the decrease was inhibited by using of intravenous anesthetics (Ravonal) or antihistamic drugs (Anergen). This was quite similar and parallel to the changes of hypotension which was caused by the reinjection of the antigen and inhibited by Ravonal and Anergen. When the anaphylactic by-effects were experimentally caused by trapsfusion of the rabbits blood with antigen to the sensitve rabbits, a severe shock resulted and γ-globulin decreased remarkably. By using of Ravonal or Anergen at that time, however, there was seen an inhibition of the decrease of γ-globulin as well as of the hypotention.