BACKGROUND: Information on the effects of early treatment of seizures on mortality is scarce. The authors assessed the survival of patients with a first generalised tonic-clonic seizure, randomised to immediate treatment (treated) versus treatment only in the event of seizure recurrence (untreated), over a 20-year period. METHODS: The authors followed 419 patients. The median follow-up was 19.7 years (range 0.2-21.5) for a total of 7867 person-years. RESULTS: 40 persons (9.6%) died during follow-up, 19 (8.9%) treated and 21 (10.3.%) untreated. The probability of surviving was 100% at 1 year, 97% (95% CI 95% to 99%) at 5 years, 94% (91-97) at 10 years and 91% (87-95) at 20 years in treated patients and 100%, 98% (95-100), 97% (94-99) and 8...