Some possible factors to predict outcome after callosotomy were investigated in a personal series composed of 36 patients. Twenty-seven of them were submitted to anterior callosotomy, 1 to posterior callosotomy and the remaining 8 patients to two stage complete division of corpus callosum. All factors, either positive or negative, do not appear completely reliable; they can be envisaged only in relative terms and do not seem to be relevant to make surgical decision or to discard surgery. In author's series, dealing specifically with drop-attacks, it clearly appeared that abrupt falls to the ground unpreceded by other epileptic features did definitely better. This was the only statistically significant datum.