Objective To study the relationship between Xsp Ⅰ restriction fregment length polymorphism (RFLP) in exon 4 of low-density lipoprotein receptor (LDLR) gene and hypercholesterolemia. Methods PCR-RFLP method was applied to determine the polymorphism of LDLR gene in 446 cases of hypercholesterolemia, 284 of borderline hypercholesterolemia and 187 normal control subjects. Results Three genotypes, X+X+, X+X- and X-X-, were found in the population. (1) The frequencies of the X+X+ genotype and X+ allele in the group with hypercholesterolemia were higher than those of the other 2 groups (P<0.05). (2) From X-X- to X+X+ genotype, cholesterol and low-density lipoprotein-cholesterol increased gradually, while high-density lipoprotein-cholesterol decreased (all P < 0.05). (3) With logistic regression analysis, LDLR genotype was associated with hypercholesterolemia. Conclusion Polymorphism in Xsp I restriction site at the exon 4 of LDLR (X+ X+ genotype and X+ allele) may be a risk factor of hypercholesterolemia in Chinese population.