The left vagus nerve was stimulated during transient forebrain ischaemia in gerbils. The animals were exposed to 3 min of forebrain ischaemic insult at 37.5 degrees C. On day 5 post-ischaemia, the animals were perfusion-fixed for qualitative and quantitative histopathological analyses. High current stimulation of the vagus nerve inhibited ischaemic neuronal damage in the hippocampal CA1 sector (p < 0.01), but low current stimulation did not (p < 0.01). These effects might have been due to inhibition of the effects of excitatory amino acids during ischaemia. These results indicate that vagus nerve stimulation might be protective to neurones subjected to ischaemic insult.