Three different monosynaptic evoked potentials (thalamocortical, interhemispheric, i.e. transcallosal, and entorhino-dentate) were used to study the paired-pulse and frequency potentiation in adult rats. A marked potentiation was seen in both neocortical responses under control conditions (up to 200%), whereas potentiation in the dentate gyrus was only moderate. Clonazepam (0.1 and/or 1 mg/kg, i.p.) antagonized the potentiation of the thalamocortical responses only, the frequency potentiation was suppressed in a dose-dependent manner, and the paired-pulse potentiation was significantly attenuated only by the higher dose of clonazepam. The potentiation of the cortical interhemispheric as well as of the entorhino-dentate evoked potentials was not changed by either dose of clonazepam. The present results do not form the hypothesis of frequency potentiation as a mechanism of epileptogenesis.