The effect of corpus callosotomy on cognitive functioning, social adjustment and motor behavior was studied in 25 pediatric patients. In order to assess age-related differences in cerebral adjustment, the sample was divided into two groups, one group operated on before and the other after the age of 13 years. Pre- and postoperative data were collected from all patients by means of standardized neuropsychological tests. When possible, the children were also submitted to simple interhemispheric transfer tasks in the tactile modality. Results revealed that all patients benefited from the callosotomy, regardless of their age and their mental capacities at the time of the surgery. The greatest improvements were observed in social adjustment. Generally, neuropsychological outcome paralleled neurological outcome. In keeping with the plasticity hypothesis, the young group showed greater gains than the older group. The latter showed similar sequelae as the adult split-brain patients described in the literature. Number of years of uncontrolled seizures was not related to neuropsychological outcome. Higher IQ was associated with better outcome in the young group, mainly because this group was more severely retarded and had more to gain from the surgery than the older group. However, mental retardation should not be an exclusion criterion for corpus callosotomy in view of the potential benefit of the surgery for the patient and his/her family.