Epileptic seizures and EEG interictal paroxysmal activity (PA) usually occur in an apparently unpredictable fashion, and a small number of patients with truly epileptic seizures may not present any PA on repeated EEGs. With the aim of increasing the possibility of recording interictal or ictal PA, several activation procedures are routinely carried out. In rarer instances, seizures seem to be more or less specifically evoked by unusual triggering procedures, or are chronologically related to biological rhythms. These different activating procedures may have different effectiveness depending on the type of epileptic syndrome. In the present paper the Authors describe the different activating procedures, both routinely employed and unusual ones. Their possible differential use with regard to the different epileptic syndromes and to the specific epileptologic history of the patient are examined. A selective use of these procedures is suggested, as an accurate choice of such techniques may increase the diagnostic usefulness of the EEG, in particular in patients whose basal recording is not contributory.