(45)Ca was injected into the abdominal cavity of normal mouse. Thereafter, (45)Ca incorporated in the blood, bone, brain, cartilago, muscle, spleen, liver and kidney was investigated, and it was observed that the concentration of (45)Ca incorporated in the various tissues was stablest 24 hours following the injection. Thus, investigations were carried out at this time to compare the concentration of (45)Ca in the various tissues of the ep-mouse to that of the normal mouse and its relative efect on the characfer of the convulsion. The results were as follows; 1) Blood (45)Ca content of the ep-mouse was higher than that of normal mouse, and this was not affected by convulsions. 2) There was no significant difference between the ep-mouse and normal mouse in (45)Ca content incorporated in the bone, nor any effect in the convulsive nature. 3) (45)Ca concentration incorporated in the brain of ep-mouse was markedly lower than that of normal mouse, this concentration was slightly increased by convulsion. 4) (45)Ca concentration incorporated in the muscle of ep-mouse was lower than that of normal mouse, and this concentration was slightly increased by convulsion.