Thirty-five SD rats were divided into 3 groups, in which 5 rats were served as control. The other 2 groups, 15 rats in each received either NGF solution or normal saline. The injury at the level of T8 spinal segment of the rat in these two groups were made by dropping a weight of 10 g from a height 2.5 cm after a total laminectomly from T7-11 segments. A thin plastic tube was inserted into the subarachnoid space below the injured segments. NGF was introduced through the tube at intervals of 1, 2, 3, 4, 8, 12, 24, 48 hours in the NGF group, and normal saline in the normal saline group. At 4, 8, 24 hours following surgery, 5 rats in each group were sacrificed and the injured segments were resected for examination. The contents of water and calcium were measured by dry-wet method and atomic absorption spectroscopy. The result showed that total calcium and water contents in normal saline group were markly increased, however, the changes of these two parametere were not so prominent in NGF group. It was suggested that NGF play a role in protecting the spinal cord by maintaining the calcium level of the injured segment.