Children with epilepsy, as a group, have a greater risk for developing learning problems as comorbid disorders. It is unknown which factors contribute to the development of such learning problems; therefore, our current knowledge does not allow the prediction of educational delay in an individual child with epilepsy. This study aimed at excluding as many factors as possible that could interfere with the analysis of the impact of epilepsy on learning. From patients referred to us in 1997 (N = 123), children were included with mild global learning impairment, defined as educational delay between 6 months and 1 year and no other apparent reason for learning impairment except for epilepsy (ie, excluding children with dyslexia, attention-deficit hyperactivity disorder, or mental handicap). A total of 44 patients fulfilled this criterion: 31 also had epilepsy (experimental group); the remaining 13 patients with similar mild learning impairment but without epilepsy were used as controls. In the experimental group two subgroups were distinguished on the basis of onset of learning impairment: in group A (n = 17) the learning problems are not unexpected as they were preceded by mild developmental delay; in group B (n = 14) the problems are unexpected and had a sudden onset. The two experimental groups differed from the control group on a number of variables, such as gender and the incidence of perinatal complications. More differences have been found between the two experimental groups: group B is selected from a larger group: all children with mild global learning impairment with sudden onset. In this group considerably more children with epilepsy have been found compared to the children with developmental delay; moreover the epilepsy is more often characterized in these children as "unexpected," that is, there was no previous established diagnosis of epilepsy, the symptoms were mostly unclear and behavioral in make-up (attentional lapses, etc); the electroencephalogram plays a much greater role in the diagnosis in this group, especially in demonstrating seizures; finally, the children in this group more frequently have neuropsychologic impairment. Children with epilepsy can have mild global learning difficulties, especially in the period after the onset of seizures. This group can be divided in a group with "trait-dependent learning difficulties," that is learning difficulties based on developmental delay, and a group with "state-dependent learning difficulties." The focus in our study was on this latter group, consisting of children with sudden and unexpected decline of results in school. The crucial finding in this group is the relatively frequent demonstration of difficult-to-detect seizures, demonstrating that an uncontrolled epilepsy can cause a decline in school results even when the seizures are of short duration and have subtle symptoms.