Studies were carried out to clearfy GABA metabolism in the brains of an epileptic, the latent cerebral local anaphylactic (L. C. L. A.) rabbit and ep-mouse administered with (14)C-GABA. 1) Incubated with a brain slice, radioactivity of (14)C-GABA was slightly detected in glutamic acid, aspartic acid and glutamine in the incubation medium. 2) In this case, most of the radioactive carbon of GABA was converted into (14)CO(2). 3) The epileptic brain appeared to decreased in the (14)CO(2)-activity, compared with the non-epileptic. In case of the epileptic brain, the activity in the focus was lower than the one in the non-focus. 4) The study with L. C. L. A. rabbit and ep-mouse could not manifest any difference in GAGA metabolism in contrast to the normal control groups.