The effects of Diamox on the cholinesterase activities in nucleus lenticularis of cats brain were measured. The experiments were performed by Ammon method taking the sanples at 9 and 24 hours respectively after the injection of Diamox. Concerning about the mean values of each 7 cases, the cholinesterase activities showed 44.8% increase at 9 hours and 43.4% increase at 24 hours. The anticonvulsive effects of Diamox were considered to be caused by the acceleration of the acetylcholin decomposition of cholinesterase from these experimental results.