A preliminary study was made on the experimental serum anaplylaxis and the followings were observed. The sensitization of rabbits was made by transfusion of cow sera as antigen. The serum calcium content was decreased by shock, but the decrease was inhibited by using intravenous anesthetics (Ravonal) or antihistamic drugs (Anergen) or hlorpromazine (Contomin). This was parallel to the changes of hypotension which was cansed by the reinjection of the antigen (cow sera) and inhibited by Ravonal, Anergen and Contomin. The serum nucleic acid content, both RNA and DNA, was increased by shock, and the inhibition by drugs was similar to the action as serum calcium content. The anaphylactic ill effects were experimentally caused by transfusion of the rabbits blood with antigen (cow sera) to the sensitive rabbits. The ill effect resulted in a severe shock, and the serum calcium content decreased and the nucleic acid content increased remarkably. The decrease of the serum calcium content, iucrease of the serum nucleic acid content and changes of hypotension were inhibited by the use of Ravonal, Anergen and Contomin in this experiment, as well as in the preliminary experimental anaphylaxis.