This study was to investigate the changes in NO - 2/NO - 3 content in the hippocampus and brainstem and its relationship with neurobehavioral alteration after whole body blast injury (WBBI) in rats. It was found that the contents of NO - 2/NO - 3 and cGMP in the hippocampus and brainstem were significantly increased 3, 24 and 120h after WBBI, and they were markedly correlated with blast injury severity. Activeavoidance response (AAR) decreased obviously, and active avoidance response latency (AARL) and escape response latency (ERL) were significantly prolonged after WBBI. The correlation analysis indicated that the changes in NO - 2/NO - 3 in brain tissues were also significantly correlated with AAR, ERL and AARL respectively. The results suggested that NO production was significantly increased in the hippocampus and brainstem after whole body blast injury. The over release of NO might be related to the blast wave induced damage to the central nervous system.