1. In cases of unilateral and bilateral frontal lobotomy, temporal slow wave activity was found to be a prominent feature, though more transient than the dominant frontal slowing. This nonfrontal slowing may be interpreted as the result of cerebral edema and hippocampal herniation from operative manipulation.2. There is an apparent correlation between the degree of slow activity in the post-operative EEG and clinical improvement, in that slight or severe degrees of slowing was found to be more conspicuous in those cases that exhibited little clinical improvement. In contrast, moderate slowing was associated with moderate to marked clinical improvement.3. The frontal slow wave activity, though decreasing in prominence, persists in the majority of cases for at least 3 years and possibly longer.Abstract Teaser