Objective. Although major and minor congenital malformations and abnormal growth parameters are known to be increased in children of women with epilepsy, their cognitive performance has not been well characterized. A better understanding of the relative effects of intrauterine exposure to antiepileptic drugs (AEDs) and maternal seizures during pregnancy on cognitive functioning in the offspring would be helpful in prepregnancy counseling and pregnancy management for women with epilepsy. Methods. Women with epilepsy (n=58) were followed prospectively with frequent monitoring of AED doses, plasma levels, and seizure occurrence during pregnancy. Their school-aged children (n=96, ages 6–16) underwent detailed neuropsychological testing (NPT). Mothers and fathers of these children underwent NPT whenever possible. A control group of 93 children of mothers without epilepsy, matched for age, education, and socioeconomic status, also underwent NPT, as did their parents. Results. Children of epileptic mothers had lower Full Scale IQ (FSIQ) scores (FSIQ=102) than controls (FSIQ=112) (P<0.01). There was no difference between the FSIQ scores of children of mothers with epilepsy who had seizures during pregnancy (FSIQ=102) and those who did not (FSIQ=103) (P=0.96). There was no difference in scores between children of mothers with idiopathic generalized epilepsy (FSIQ=101) and children of mothers with partial epilepsy (FSIQ=103) (P=0.56). Children exposed to polytherapy had lower scores (FSIQ=100) compared with those exposed to monotherapy (FSIQ=104), but the difference was not statistically significant (P=0.31). Scores of children exposed to phenytoin (FSIQ=105) and carbamazepine (FSIQ=103) monotherapy in utero did not differ significantly (P=0.68). Conclusions. Cognitive ability was significantly reduced in children of women with epilepsy. Our study suggests that this is due to intrauterine AED exposure rather than to maternal seizures during pregnancy. Further analyses will be carried out by trimester and on specific subtests of the NPT battery.