Minimal, maximal, or sham seizures were chronically administered to 168 male Wistar rats 3 or 5 times per week for 4,8,12, or 16 wk. Regional analysis of the brains revealed that increase in weight of the whole brain of electroshocked Ss reported previously was confined to the cortex-especially ventral cortex, including hippocampus and amygdala. Total protein and total AChE actively increased throughout most of the brain in proportion to increase in weight. Specific ChE activity decreased in the cortex of electroshocked Ss, especially visual and ventral cortex. Electroshocked Ss given maximal seizures 5 times per week performed more poorly than controls on a spatial discrimination test in an underwater T maze.