Osteonecrosis of the femoral head (ONFH) is a multifactorial disease and certain individuals are more at risk or may be predisposed to it. An altered lipid metabolism is one of the major risk factors for osteonecrosis, especially corticosteroid therapy and alcoholism. 3-hydroxy-3-methylglutaryl coenzyme A. (HMG-CoA) reductase inhibitors, stalin used as lipid-clearing agent, have been known to decrease the risk of osteonecrosis in patients receiving steroids and affect coagulation and fibrinolysis. Therefore we evaluated the association of HMG-CoA reductase gene polymorphisms and haplotypes between osteonecrosis patients and normal controls. We directly sequenced the HMG-CoA reductase gene in 24 Korean individuals, and identified five sequence variants. Four SNPs (-6933C>T, -6045T>G, +12673G>A, and +18128C>T) were selected and genotyped in 349 male ONFH patients and 300 male control subjects. The genotypes, allele frequencies, and haplotypes of the polymorphisms in the total patients as well as in the subgroup by etiology were not significantly different from those in the control group. In addition, no significant differences between each genotype of the polymorphisms and plasma lipid level could be found in the control group. These results suggest that the polymorphisms and haplotypes of HMG-CoA reductase gene are unlikely to be associated with a susceptibility to ONFH.