Ponies were administered at the level of 0.1mg per kg of body weight of acetylpromazine malate through the jugular vein. Sedative effect, clinical signs such as body temperature, and changes of red blood cell counts and serum glucose concentration were investigated. Sedation was induced 5 to 6 minutes after injection of acepromazine and sedative effect was lasted for 30 to 40 minutes. Responsive reactions, however, to external stimuli were remained. Change of body temperature was not observed and heart beat was increased at the stage of induction and respiratory rate was decreased during the sedative period. Red blood cell count was considerably decreased during sedation, and concentration of serum glucose showed a tendency to increase gradually from the induction.