Abstract: Cerebral concussion was produced with an iron pendulum hitting in rats, which resulted in loss of consciousness lasting 1 to 6 minutes The rat recovered soon without focal neurological signs The energy absorbed by the head at impact was calculated to be about 2.35 J. The routine pathological observation showed the changes of congestion, edema, and small focal hemorrhage in the brain tissues. A remarkable time course of pathological alterations were observed. After concussive injury, the brain vessels showed spasmodic contraction at 15 vain. The above nonidiosyncratic alterations began at 1h, reached a peak at 6h, retarned to the level of the 1h at 24h and disappeared at 48h. with weil's staining, swelling of the axons and the myelin sheaths were revealed. The lesions of retraction bails began to appear at 6h after injury and lasted to 24h and 48h.