Idiopathic generalized epilepsies (IGE), in some cases, have focal features in the kinematic of seizures and in the EEG. The aim of the paper was to study these clinical phenomena using video-EEG monitoring. We studied 180 patients (80 men and 100 women) with different forms of IGE with epileptic seizures recorded with this method. The effect of the "superposition" of focal electro-clinical features on the kinematic matrix and EEG pattern of the generalized myo- (clonic)-tonic-clonic seizures was noted. The authors suggest to discuss the definition of the "phenomenon of secondary focalization". This is the clinical/electroencephalographic phenomenon developed in IGE and presented by the appearance of secondary focal features (clinical and electroencephalographic) in the structure of the generalized epileptic seizure. The evidence for the secondary generalization of the seizure with the presence of the regional cortical ictogenic source as well as the diagnosis of focal epilepsy are the exclusion criteria for the phenomenon of secondary focalization.