Abstract： Objective　To observe the effect of aloe-emodin on the expression of proliferating cell nuclear antigen (PCNA) in smooth muscle cells (SMCs) after arterial injury and study the molecular mechanism of inhibition of aloe-emodin on SMC proliferation.Methods　Deendothelialization was performed at the abdominal aorta in Japanese white rabbits using a 3F Fogarty arterial embolectomy catheter. 48 hours later, the medium of abdominal aorta was isolated and primary SMCs culture was performed. Cells were synchronized to G0 by serum starvation, then aloe-emodin at a concentration of 20?μg/ml was added to the culture medium containing 10%［v/v］ fetal calf serum. Vehicle was also added to the medium as a control. After 18 hours, the expression of PCNA at the level of mRNA and protein were examined using techniques of RT/PCR, Western blotting and inmmunocytochemistry respectively. Results　Compared with the control group, the expression of PCNA mRNA and protein was prominently decreased after addition of aloe-emodin. Conclusion　The inhibition of aloe-emodin on SMCs proliferation may be caused by inhibiting the expression of the PCNA gene.