Normal somatosensory evoked potential (SEP) as well as changes after incomplete cerebral ischaemia following bilateral carotid artery occlusion (BCO) were characterized in the Mongolian gerbil. BCO significantly decreased cerebral blood flow (CBF). Reperfusion CBF at 10 min and 2, 3 and 4 h was significantly below preischaemic control values. BCO decreased SEP amplitude but had no effect on EP-P3 central conduction time. BCO did significantly increase EP-P11 central conduction time. Reperfusion amplitudes at 10 min and 2, 3 and 4 h revealed a significant increase only at 4 h when compared to the ischaemic amplitude. EP-P11 central conduction time at 10 min reperfusion showed dramatic improvement compared to ischaemic values, although values at 2, 3 and 4 h reperfusion were not statistically different from ischaemic values. A separate group of animals prepared identically but without BCO showed no significant changes in either SEP or CBF over time. These studies establish the protocol necessary to measure SEP in the Mongolian gerbil. In the future SEP may be used as an integral tool in the study of the primary determinants of neurophysiological recovery following cerebral ischaemia.