1. Serum aldalase activity markedly increased after convulsion caused by metrazol injeotion, about twice of the preconvulsive level, and recoverd to the normal level after 1 hour. 2. Same results were observed in the repetitive convulsion caused by hexogen administration. 3. During convulsion, brain aldolase activity did not change, muscle aldolase activities were slightly decreased. 4. In such cases succinyl choline chloride was injected into the rabbits no acceleration was observed in the serum aldolase activity. 5. Therefore, the acceleration of serum aldolase activity in the experimental convulsion was due to the muscle albolase in such a condition.