© 2022 Istanbul University Press. All Rights Reserved.Objective: Studies on the actions of exogenous agmatine in experimental models have shown its anti-convulsant effects. However, there are no findings regarding the influence of agmatine on absence epilepsy. Therefore, we investigated the effects of the agmatine in the occurrence of spike-and-wave discharges (SWDs) in the Wistar Albino Glaxo Rijswijk rats (WAG/Rij) model of genetic absence epilepsy. Materials and Methods: Three different doses (20, 40 or 80 mg/kg) of agmatine or saline were administered intraperitoneally to the adult WAG/Rij rats, and electroencephalography (EEG) was recorded for 2.5 hours. The number and the mean and cumulative durations of SWDs were measured. The SWD frequency characteristics were quantified by means of average power-spectra of the first 2nd segments of the SWD complexes before and after the effective dose of agmatine. Results: Agmatine, administered 80 mg/kg systemically, temporarily increased the number and cumulative duration of SWDs compared with saline injected WAG/Rij rats. This effect of agmatine, however, was not associated with any change in the frequency characteristics of the SWD complexes. There was no effect on neither the incidence nor the cumulative duration of SWDs when agmatine administered in lower doses (20 or 40 mg/kg). Conclusion: Higher doses of agmatine temporarily and slightly increase the incidence of SWDs in WAG/Rij rats, which may suggest its possible aggravating activity in absence epilepsy patients through its activity on adrenergic, serotonergic and AMPA receptors.