The effects of the GABAergic drugs nipecotic acid, Gabrene, baclofen and metatolylcarbamide (MTC), when given alone or in combination at subthreshold doses with AT II also at a subthreshold dose effective on PTZ-kindling in mice were studied. PTZ-kindling was provoked by intraperitoneal (i.p.) injections of PTZ (40 mg/kg) every other day in male albino mice until clonic seizures appeared. Nipecotic acid (100 and 200 micrograms/mouse intracerebroventricularly [i.c.v.]) tended to decrease seizure intensity. Gabrene (25, 50, 100 and 250 mg/kg i.p.) inhibited PTZ-kindled seizures. Baclofen at a doses of 2.5 and 5 mg/kg i.p. tended to decrease seizure intensity and at a dose of 10 mg/kg was ineffective at all. MTC (50 and 75 mg/kg i.p.) tended to decrease and at a dose of 100 mg/kg significantly decreased seizure intensity. Combinations of subthreshold dose of AT II (0.05 micrograms/mouse i.c.v.) and subthreshold doses of nipecotic acid (100 micrograms/mouse) or Gabrene (10 mg/kg) or baclofen (10 mg/kg) or MTC (50 mg/kg) significantly decreased the intensity of PTZ-kindled seizures in mice. The observed potentiation of the anticonvulsive activity on PTZ-kindling suggests interactions of AT II receptors with GABA receptors (GABAA, GABAB or both), effected through allosteric mechanisms.