Abstract: Objective To compare the MspI geno type polymorphisms of cytochrome P4501A1(CYP1A1)gene between Mongolian and Han studengts.Methods The genotype polymorphisms was analyzed by PCR restriction fragment length polym orphisms(RELP)of the CYP1A1 gene with the restriction enzyme MspI in 60 Mongolian and 60 Han students.Results CYP1A1 geno type frequencies were 33.3% for homozgous wild type(wt/wt),48.3% for heterozygote(wt/wt),and 18.3% for homozygous variant(vt/vt)in the Mongolian students.Among the Han students,the frequencies of homozygo us for wild type(wt/wt),heterzygote(wt/wt)and homo zygous variant(vt/vt)of CYP1A1 were 35.0%,51.7% and 13.3%,respectively.Chi squaretests showed no significant difference between the two groups(P>0.05).Conclusion The CYP1A1 geno type frequencies in the Mongolian and Han students of Inner Mongolia showed no statisical difference.