We studied 18 patients with generalized tonic-clonic seizures. The signs of idiopathic epilepsy were as following: normal physical and neurological status, seizures of awakenings, peculiarity of circadian rhythms ("owls"), hyper synchronous type of EEG. The EEG and MRI study revealed insignificant epileptiform or structural changes. The authors consider these findings as possible phenocopies of idiopathic epilepsy.