To study changes in mRNA expression of induced nitric oxide synthase (iNOS) in the brain of rat repeatedly exposed to +Gz, and to explore the prevention and treatment effect of basis fibroblast growth factor (bFGF) and radix salviae miltiorrhizae (RSM) on the brain injury induced by repeated +Gz exposures. The mRNA expression levels of iNOS in brain were measured by semi quantitative reverse transcription polymerase chain reaction (RT PCR). The results showed the iNOS mRNA expression level in brain of rats repeatedly exposed to +Gz was significantly higher than that of control, but bFGF and RSM could alleviate the expression change of iNOS. It suggested that the iNOS mRNA expression in rat brain was induced by repeated +Gz exposures and it might play an important role in the pathologic course of brain damage induced by +Gz exposures.The bFGF and RSM possessed prevention and treatment on the brain injury induced by repeated +Gz exposures.