All children aged 0-19 years who had active epilepsy in a defined Swedish population were traced and given a clinical and psychometric investigation. Twelve years later, a follow-up study was carried out. Eleven of the 194 children had died, 8 of whom had had signs of neurodeficit, i.e., abnormal neurology and/or mental retardation. A long-standing remission of seizures occurred in 124 of the 194 children. Signs of neurodeficit, frequent seizures, and many types of seizures were negative prognostic factors. The presence of all these factors carried a bad prognosis, seizures persisting during 12 years in greater than 80%. For those who were mentally and neurologically normal and had low seizure frequency, prognosis was excellent, only 11% still having active epilepsy after 12 years. A study of the annual remission rate showed that each year approximately 13% of the children without neurodeficit had remission from epilepsy the next year. This rate appeared to be stable over the 12 years studied. Among those children with neurodeficit, the annual remission rate was high only during the first years after onset, later falling to 3% a year.