OCCASIONAL SPECIMENS of scarred, atrophic brain removed for the relief of focal cerebral seizures at the Montreal Neurological Institute have shown striking perivascular collections of round cells, particularly in less severely damaged areas of these specimens. In the past this perivascular cuffing has been attributed to the effect on the brain of recurring seizures, with recognition, however, that this was a rather unsatisfactory explanation since the great majority of surgical specimens removed from patients with equally frequent focal seizures do not show this change. Histologic studies of surgical specimens from three children recently operated upon for intractable focal seizures suggest that this microscopic picture may indicate the presence of an unsuspected, more or less localized, chronic encephalitis that has smoldered along over a period of years. The clinical and histologic data on these three children will be reported in some detail.