The aim of the study was to evaluate the influence of precipitating factors and therapy on the outcome of epilepsy with generalized tonic-clonic seizures.Retrospective analysis of data from 34 patients (mean age at seizure onset 19 years; mean duration of follow-up 9.2 years) suffering from epilepsy of either cryptogenic or remote symptomatic (n = 19), or idiopathic (n = 15) etiology. The total number of seizures in all patients was 146.Without treatment 97 seizures manifested during 90.5 years without treatment (1.07 seizures/year), during treatment with carbamazepine or valproate 49 seizures occurred within 224 years (0.2 seizures/year). The frequency of seizures was significantly lower during treatment. Precipitating factors were found in relation to 31% of seizures in patients with remote symptomatic or cryptogenic epilepsy, and for 51% of seizures in patients with idiopathic epilepsy.There was a low frequency of seizures in patients with generalized tonic-clonic seizures. Precipitating factors are common. Antiepileptic drug treatment is effective.