By means of a prospective study, relapse after discontinuation of antiepileptic drug treatment in 433 children with epilepsy and 40 patients who were treated after the first seizure was investigated. Independent of the electroencephalographic findings, the age of the patients, and other factors, the antiepileptic drugs were reduced during 1, 3, 6, and 12 months after 2, 3, and 4 seizure-free years; and in children with absences after 1, 2, 3, and 4 seizure-free years. The observation period after stopping therapy was at least 3 (on average, 5-6) years. In 157 of 433 children (36.3%) and 5 of 40 patients (12.5%), relapses occurred during this time. More than half (61.8%) of the relapses occurred during the withdrawal period or within 3 months: altogether, 86% within 1 year after discontinuation of therapy. Eighty-six percent of these patients again became free from seizures on administration of the original therapy. The dependence on predictive factors of the rate of relapse was tested by multivariate statistical analysis. There was a pronounced significant dependence on the duration of the seizure-free period, the duration of the withdrawal period, the length of illness, the frequency and duration of seizures, and the presence of paroxysmal activity in the EEG at the start of the discontinuation of antiepileptic drug treatment. The stopping of therapy during the pubertal period did not present a higher risk.