Antiepileptic drugs have been reported to have a variety of adverse effects on behavior and performance in children with epilepsy. Previous studies investigating these side effects, however, have not controlled for the baseline status of the child (e.g. underlying neurological condition, seizure type, socioeconomic status, family variables), making it difficult to determine whether changes in function are attributable to the use of medication. We investigated the cognitive and behavioral profiles of 43 children, aged from 4 to 16 years, with new onset, idiopathic seizures. Twenty-six of these children participated in a 6-month follow-up study, and 12 in a 12-month follow-up study, investigating the effects of antiepileptic medications on psychological functioning. The children were of average intelligence (mean 1Q108) and had not previously been treated with antiepileptic medication. Children were classified as having either generalized convulsive, generalized non-convulsive (absence), simple partial, or complex partial seizures. Prior to the initiation of treatment, children with partial seizures were found to perform better than children with generalized seizures on measures of cognitive functioning. Children with convulsive seizures obtained significantly higher cognitive scores than those with non-convulsive seizures. Children with generalized non-convulsive seizures had lower cognitive scores than subjects with other types of seizure. No differences were found between groups at baseline prior to the initiation of antiepileptic medications. Analysis of subjects' performance after 6 and 12 months of antiepileptic therapy showed no significant deterioration attributable to medication. The differences in cognitive performance of the four seizure groups at baseline were not apparent at the time of follow-up. These results indicate that intrinsic and environmental variables may play a more significant role in predisposing certain children to cognitive and learning problems than do antiepileptic medications.