Objective To investigate the protective effects of FUZHENGJIEDU,a kind of Chinese herb on rats exposed to radon and it's daughter.Methods Twelve male SD rats were exposed with concentration of 40 000 Bq/m3 radon and the exposed dose was 120 work level month (120 WLM),and then all the rats were randomly divided into 2 groups.One group was 120 WLM group (positive control,n=6 ),the other group was FUZHENGJIEDU treatment group (120 WLM exposed rats were given FUZHENGJIEDU 5.0 g every day,n =6),meanwhile 6 rats which lived in the normal environment ( the concentration of radon and it's daughter was lower than 50 Bq/m3 ) as control group.The levels of tumor markers induding carcinoembryonic antigen ( CEA),neuron-specific enolase (NSE),CYFRA21-1 and p53 antibody were tested by ELISA.The rate of p16 gene methylation was measured by methylation-specific PCR (MSP).Results The levels of CEA and NSE in 120 WLM group were (396.62 ± 148.74) and (9.09 ±0.90) μg/L,respectively,significantly higher than those of control group (t =2.583,2.463,P ＜ 0.05).The levels of CEA and NSE in treatment group were (70.89 ±44.71) and (4.31 ±1.37) μg/L,respectively,remarkably lower than those of 120 WLM group (t =2.921,2.526,P ＜0.05 ).The concentrations of CYFRA21-1 and p53 antibody were not significantly different among the three groups (t =1.713,1.963,P ＞ 0.05 ).The rate of p16 gene methylation in BALF cells in 120 WLM group was 16.67％,but in control group and treatment group did not arise p16 gene methylation in BALF cells.Conclusions FUZHENGJIDU would decrease the levels of CEA and NSE and the rate of p16 gene methylation,and could exert it's protective effect on rats exposed to high concentration of radon.