Objectives By observing γ radioactive 103Pd stent affecting the proliferation and apoptosis of vascular smooth muscle cells (VSMCs) to explore the mechanism of radioactive stent preventing in-stent restenosis. Methods Fifty male New Zealand rabbits were randomized into stent group and 103Pd stent group. Control group was set up. The materials were harvested on 3, 7, 14, 28, 56 days after operation and the following investigations were carried out, including pathomorphology, immunohistochemistry, apoptosis (TUNEL) and in situs hybridization studies. Results ①The severity of the stenosis in 103Pd stent group was less than that of stent group.It was the most obvious on 56th day (P ＜ 0.01).②The expression of PCNA of 103Pd stent group was lower than that of stent group on 3 to 28 days. It was the most obvious on 7th day, 16.35%±0.79% vs 24.36%±0.55% (P＜ 0.01 ). ③TUNEL method showed that the 103Pd stent group had much more apoptosis of VSMCs than that of stent group. The highest rate of apoptosis appeared on day 7, 14.72%±0.53% vs 12.42%±1.13% (P＜0.01). ④ By calculating the ratio of PCNA/apoptosis (P:A), a much lower ratio was seen in 103Pd-stent group than that of stent group at 3 to 28 days. There was significant statistic difference between two groups (P＜0.05). ⑤For bcl-2/bax ratio, the result in 103Pd-stent group was lower than that of stent group at 3 to 28 days. It had significant statistic difference (P ＜ 0.05). Conclusions γ radioactive stent can inhibit the proliferation and accelerate apoptosis of injured media VSMCs. Also it can decrease the ratio of proliferation to apoptosis and relieve the severity of restenosis.