Early neuropsychological changes following partial anterior callosotomy were evaluated in 15 patients with epilepsy (10 secondary generalized and 5 Lennox-Gastaut syndromes) by comparing their performances 1 month before surgery and then 15-20 and 90-100 days postoperatively without modifying the anticonvulsant treatment. The following neuropsychological and motor functions were tested: memory, attention, visuo-motor ability, posture, motor dexterity, language, praxis and gnosis. Social behaviour was also investigated. The main results are as follows: (i) most cognitive functions showed no significant variation; (ii) motor organization was still slightly impaired at the second check-up after the surgery; (iii) improvements in social behaviour and posture were frequently observed at the final evaluation. The analysis of individual cases highlights the influence of the extent of commissurotomy, lesions related to the surgical procedure and preoperative brain damage in determining the post-surgical profile. On this basis, the short-term neuropsychological cost of partial callosotomy appears to be low and seems to depend mostly on surgical parameters and brain conditions before the operation.