Objective To investigate the effect of ketamine injected via the radicular arteries on spinal cord. Methods Twenty healthy mongrel dogs of both sexes weighing 12-18 kg were randomly divided into 2 groups ( n = 10 each): control group (group C) and ketamine group (group K). The animals were anesthetized with intravenous pentobarbital 30-35 mg/kg, fentanyl 50-100 μg and vecuronium 0.2 mg/kg and maintained with propofol ically ventilated after tracheal intubation. A catheter was inserted into T8 poster intercostal artery and advanced toward the opening of radicular artery which supplies the spinal cord. Ketamine 100 mg (in 2 ml of normal saline)was injected via the catheter in group K. Three hours after ketamine administration, the animals were sacrificed. A 1.5 cm long segment of spinal cord at the level of T8 was removed for microscopic examination and determination of the expression of NSE, S100β and Tau protein by immuno-histochemistry. Results There was no significant difference in the number of Nissl' s staining-negative neuronal cells and the expression of NSE, S100β and Tau protein in the spinal cord between the 2 groups ( P ＞ 0.05 ). Conclusion Ketamine injected via the radicular arteries does not induce spinal cord injury.