behavioural changes during the three-week period, except for one rabbit in the NS group that showed decreased appetite and activity, and weight loss. By LM, abnormal findings were observed in two rabbits in the NS group; these were thought to be the result of trauma and infection associated with epidural catheterization. EM findings showed no significant neurotoxic findings in either group. In conclusion, epidurally-administered HA did not cause neurotoxicity in rabbits