A cohort of 119 two- to 16-year-old patients was followed to assess the risk of recurrence after a single, unprovoked, generalized tonic-clonic seizure. Only children with a normal neurological examination and intellectual development, and an EEG showing no focal abnormality, were studied. The risk of recurrence at six months was 22 per cent, at one year 28.5 per cent, at three years 32.6 per cent and at eight years 37.7 per cent. 58 per cent of recurrences occurred within the first six months and 87 per cent within the first two years. Initial EEGs showing generalized, unprovoked spikes and waves, generalized paroxysmal discharges precipitated by intermittent photic stimulation, or isolated slowing, were associated with risks of recurrence at two years of 40, 50 and 26 per cent, respectively. These results do not differ significantly from those obtained when the initial EEG was normal (29 per cent). Age, seizure duration and history of epilepsy in the family were not associated with a significantly higher risk of recurrence. The risk of recurrence was similar for treated and untreated patients.