This study was aimed at the mechanism of resistance to fluoroquinolones in Staphylococcus aureus isolated from patients in Chengdu. The relationship between the point mutations in the gyrA genes and the resistance of 63 strains (57 fluoroquinone-resistant strains and 6 wild types) isolated clinically in Chengdu were investigated by a combination of restriction fragment length polymorphism analysis. The results revealed that there are 67.27%-92.5% of the fluoroquinolone-resistant strains against norfloxacin, fleroxacin, tosufloxacin, cipofloxacin, ofloxacin and sparfloxacin had a Hinf I site mutation in the gyrA genes, and most of such strains with such mutation in the gyrA genes showed high-level resistance. These indicate that Hinf site mutation in gyrA genes is the mainly cause of the resistance of fluoroquinolone-resistant strains of Staphylococcus aureus in Chengdu region.