Abstract: Objective To observe the impact of natural plant Pteris vittata on arsenic(As)excretion in rats.Methods Fifty rats were randomly divited into normal,model,positive control,low and high dose group(10 rats in each group).Excepted for the normol group,all groups received intraperitoneal injection of sodium arsenite(2 mg/kg)5 days a week for 4 weeks.Low and high dose group received feeds containing Pteris vittata for 6 weeks.Positive control group received intramuscular injection of sodium dimercapto-sulphonate(DMPS).Urine and blood As in rats was detected dynamically.Two weeks after the As injection,blood heamoglobin(Hb),creatinine(Cr),blood urea nitrogen(BUN),and aspartate transaminase(ALT)were detected.Then,all the rats were dissected and their organ coefficient and micronucleus rate of polychromatic erythrocytes of bone marrow were calculated and compared.Results In the 4th weeks of As exposure,urine As in high dose,low dose,model and DMPS group were 6.06±0.61,3.45±0.79,2.48±0.27,and 6.63±0.68 mg/L,respectively.Urine As in high dose group was significantly higher than that of the model group(P<0.01).The As excretion of high dose group was similar to that of DMPS group.There were no obvious changes observed in Hb,Cr,BUN,ALT,and organ coefficient of liver and kidney.The increased micronucleus rate of polychromatic erythrocytes induced by As was inhibited in high dose group.Conclusion Extracted Pteris vittata has obvious impact on As excretion.No obvious damage effect was observed in the rats with continuous feeding of Pteris vittata for 42 days.