Abstract: AIM To study the effect of Rosuvastatin on intimal hyperplasia and PTEN expression changes after balloon catheter injury in rat carotid artery. METHODS 48 male SPF SD rats were equally divided into Group A and Group B, and then subjected to balloon catheter injury on the left carotid artery. Group B rats were given Rosuvastatin(dissolved in Nacl, gavage) at the dosage of 5 mg/(kg·d) 3 days before the injury, while Group A rats were given vehicle instead. The left carotid arteries of both Group A and Group B rats were respectively defined as the injured group and the Rosuvastatin group, then the right artery of Group A as normal control. Both Group A and Group B rats were sacrificed at 7 days or 14 days after injury, and Both sides of common carotid arteries were harvested. Intimal hyperplasia and the expression of total PTEN and P-PTEN protein were determined by HE staining and Western blot analysis. RESULTS Forty rats were included. ①Neointimal formation was observed on 7th day after balloon injury and increased intimal area became significant in 14 d injured group, accompanied with increased area ratio of intimal/media and reduced lumen area (compared with normal control group, P<0.05). Lumen area in 14 d Rosuvastatin group increased by 26% than that in 14 d injured group（P<0.05）. ②The expression of total PTEN, and phosphoPTEN and the ratio of phosphoPTEN/total PTEN increased in injured group compared with the normal control group(P<0.05). However, that ratio decreased significantly in Rosuvastatin group compared with that the injured group (P<0.05). CONCLUSION ①Rosuvastatin could inhibit intimal hyperplasia of rat carotid artery after balloon injury. ②Rosuvastatin could decrease the ratio of phosphoPTEN/total PTEN. ③There might be some relativity between these two aspects above.