This study aimed at investigating the effect of quercetin on neointima hyperplasia in the abdominal aorta of rats after balloon injury and expressions of related growth factors. Fifty-four healthy male Sprague-Dawley rats were randomly divided into five groups: a sham-operation group (sham, n=6), a control group (control, n=12), and three quercetin-treated groups: Q50 group (50mg/kg body weight/day, n=12), Q100 group (100mg/kg body weight/day, n=12), and Q200 group (200mg/kg body weight/day, n=12) 3 days before balloon injury until the end of the experiment. Fourteen days after injury, rats were killed, and the abdominal aortas were harvested. Hematoxylin-eosin staining showed that quercetin significantly reduced the neointimal areas and the intimal to medial ratio in the Q100 and Q200 groups 14 days after injury. Immunohistochemical analysis showed that quercetin significantly inhibited PCNA, PDGF-BB, b-FGF, and TGF-beta1 expressions in the neointima. Masson's trichrome showed that quercetin significantly reduced collagen deposition in the neointima. We concluded that quercetin significantly inhibited neointimal hyperplasia in rat abdominal aorta 14 days after injury in relatively high doses. This effect of quercetin might be partially attributed to the suppression of PDGF-BB, b-FGF, and TGF-beta1 expressions.