The callosotomy on drug-resistant epileptic seizures may abolish or reduce their frequency and may modified the morphology of different kind of seizures. Our series is composed of 36 patients. Drop-attacks and complex partial seizures (CP) were present in all patients, generalized tonic-clonic seizures (GTC) in 16 (44.4%) and simple partial seizures (SP) and myoclonic attacks (MY) in 6 patients each. We found two kinds of modifications: a) lateralization of hypotonia which becomes hemisomatic, with lateral bending to the hypotonic side; b) different way of falling, due not only to the lateralization of hypotonia but also to the gradual impairment of muscle tone. Modifications in CP mainly concerned automatisms, which disappeared in 39.1% of patients, while 34.8% of them had a significant reduction in automatisms; this reduction consisted in simplification of automatic movements and in shorter duration of seizures.