One thousand eight hundreds and eighty patients with symptomatic and cryptogenic forms of focal epilepsy have been studied. Ninety patients (4.7%) had the secondary bilateral synchronization (SBS) syndrome in the EEG. Criteria of the syndrome are the presence of focal epileptiform activity in the EEG and SBS detected during the long-term video-EEG monitoring. In this group of patients, secondary generalized tonic-clonic, myoclonic and complex partial seizures were found. The clinical presentations of focal epilepsy were similar to the syndromes of idiopathic epilepsy in most cases. Long-term video-EEG monitoring is a method of choice in the instrumental diagnostics of these forms of epilepsy which are different in genesis and prognosis but similar in the kinematic characteristics.