The present study was an attempt to determine whether the facilitative effect of Ra could be found in rats with unilateral anterodorsal (CAl field) hippocampal lesion in the rearing escape/avoidance situation. Obtained results showed the facilitative Ra in rats with the hippocampal lesion. This suggests that the anterodorsal hippocampus might play a critical role for the establishment of the avoidance responses, but because of jumping Ra dominancy rather than rearing Ra dominancy, the question of whether the facilitative effects might be due only to increased activity induced by the hippocampal　lesion remains to be answered.