OBJECTIVE: To investigate the effect of physical training on cerebral structure and spatial learning and memory in neonatal rats submitted to hypoxic-ischemic brain damage (HIBD). METHODS: Forty-eight 7-day-old Sprague-Dawley rats were randomly divided into three groups: a group that was subjected to left carotid ligation followed by 2 hrs hypoxic stress (HIBD); a group that received physical training 2 weeks after the HIBD event; a control group that was subjected to a sham-operation without ligation and hypoxic stress. Following four weeks physical training, motor function test and water maze tasks were performed. Bilateral brain weight, cerebral morphology and left hippocampal ultrastructrue of the animals were examined. The expression levels of phosphor calmodulin-dependent protein kinase II (CaMKII) and brain derived neurotrophic factor (BDNF) were determined by immunohistochemistry. RESULTS: Compared with the control group, the motor function and the spatial learning and memory ability in the non-trained HIBD group were significantly decreased, whereas there was no significant difference between the trained-HIBD and the control groups. The left hemisphere weight and neurons in the left hippocampal CA1 zone of both HIBD groups decreased and the reduction was more significant in non-trained HIBD group. The ultrastructure of the left hippocampus was remarkably abnormal in the non-trained HIBD group, while no obvious abnormality was observed in the trained HIBD and the control groups. Phosphor-CaMKII and BDNF expression in the left hippocampus in the trained HIBD group increased significantly compared with that in the non-trained HIBD group. CONCLUSIONS: Physical training can restrain brain damage and ameliorate spatial learning and memory impairments in rats with HIBD.［Chin J Contemp Pediatr, 2010, 12 (5):363-367］