Abstract: Objective To study the relation ship of glutathiones transferase M1(GSTM1)polymorphism and lung cancer susceptibility in a Mongolian population.Methods The multip lexpolymerase chain reaction were used to analyze the genetic polym orphism of GSTM 1 among 325 healthy Hannationality,310 healthy Mongolian nationality,and 304 Mongolian lung cancer patients.The relationship between the polymo rphism of GSTM 1 and susceptibility of lung cancer in the Mongolian population was studied.Results The frequency of GSTM 1 of healthy Mong olian was 6.61% for GSTM 1(+),38.39% for GSTM 1(-)and that of Han was 57.23% for GSTM1(+),42.77% for GSTM 1(-).Chisquare tests showed that there was no sign-ificant difference between the two guoups(P<0.05).The fequency of GSTM1(+)and GSTM 1(-)of lung cancer guoup and healthy Mong olian guoup were 52.96%,47.04% and 61.61%,38.39%,respectively.The Chisqua rete sts showed that there was a significant difference between the two guoups.The people carriying with GSTM 1(-)genoty pe had a 1.43 folds increased risk of lung cancer than those carrying with GSTM 1(+)with a 95%CI of 1.03-1.96.Conclusion There is no significant difference in the frequency of GSTM 1 gene between the healthy Mongolian and Han Nationality.GSTM 1(-)is a susecptibility factor of lung cancer for Mongolian Nationality in Inner Mongolia.