Objective To investigate the effect and mechanism of Imatinib mesilate (Imatinib) on intimal hyperplasia of rabbit carotid arteries after balloon injury. Methods Thirty adult Newzealand rabbits were randomly divided into three groups: group A, B and C. Their right carotid arteries were injuried then administered with 0, 25 or 50 mg/kg of Imatinib daily for 14 consecutive days when the rabbits were sacrificed. The carotid arteries were harvested and sectioned for HE-staining and immunohistochemisty staining. Real-Time PCR was used to examine transcription levels of PDGF-B and PDGFR-β mRNA. The plasma level of PDGF-BB was assayed by ELISA. Results Arterial intimal hyperplasia and stenosis following balloon injury were seen in three groups. Thickness and area of neointima, ratio of thickness of intima to media, ratio of area of intima to media and mRNA level of PDGF-β are all higher in group A than those in group B than those in group C (P< 0.01). By contrast, the mRNA transcription level of PDGFR-β increased significantly in group C than that in group A (1.236±0.356 vs 0.708±0.372; t=2.91; P<0.01). Plasma level of PDGF-BB increased in all three groups after balloon injury than that in the baseline (P<0.01). The transcription level of PDGF-BB is higher in group A than that in group B and in group C (ng/L:23.464±3.542, 19.504±2.454, 16.588±1.207, F=17.322, P<0.05). There was no difference between group B and C. There was positive correlation between mRNA transcription level of PDGF-B and plasma level of PDGF-BB (r=0.806, P<0.01). Conclusion Vascular injury can cause intimal hyperplasia and increased PDGF-B mRNA transcription. Imatinib mesilate could inhibit the intimal hyperplasia through down regulating PDGF-B mRNA transcription. [ABSTRACT FROM AUTHOR]