Abstract: Endovascular radiation is a promising technique to substantianlly reduce the restenosis post-PTCA. Inhi-bition of VSMCs by radiation is thought as the main cause, but the machanism of this is not clear. Inhibition of VSMCs proliferation and miagration by radiation is ragarded as the most important factor. The role of apoptosis in this couse is not determined. However, inhibition of macrophage and cytokines by radiation is emphasized recently.