Nigella sativa oil (NSO), a herbaceous plant, has been used for thousands of years for culinary and medical purposes. This study aimed to investigate the anticonvulsant and antioxidant activities of NSO on pentylenetetrazol (PTZ) kindling seizures in mice. Nigella sativa oil was tested for its ability (i) to suppress the convulsive and lethal effects of PTZ in kindled mice (anti-epileptogenic effect), (ii) to attenuate the PTZ-induced oxidative injury in the brain tissue (antioxidant effect) when given as a pretreatment prior to each PTZ injection during kindling acquisition. Valproate, a major antiepileptic drug, was also tested for comparison. Both substances studied significantly decreased oxidative injury in the mouse brain tissue in comparison with the PTZ-kindling group. Nigella sativa oil was found to be the most effective in preventing PTZ-induced seizures relative to valproate. Nigella sativa oil showed anti-epileptogenic properties as it reduced the sensitivity of kindled mice to the convulsive and lethal effects of PTZ; valproate was ineffective in preventing development of any of these effects. The data obtained support the hypothesis that neuroprotective action of NSO may correlate with its ability to inhibit not only excessive reactive oxygen species (ROS) formation but also seizure generation. (c) 2005 Elsevier Ltd. All rights reserved.