Objective To study the changes and its clinical prognostic value of plasma endothelin 1 (ET-1) and P-selectin on early in-stent restenosis after percutanous intervention (PCI) in patients with acute coronary syndrome (ACS). Methods Venous blood samples were drawn from a total of 108 patients who underwent PCI before and right after the operation, as well as at 1 week, 2 weeks, 1 month, 3 months and 6 months post-procedure. Plasma was separated immediately by centrifugation at 4℃ and stored at -70℃ until detection. All patients received coronary angiography after six months and were catagorized into the restenosis and non-restenosis group according to the result. Plasma levels of ET-1 and P-selectin of the two groups were analyzed. Results Four cases received acute PCI died and another 4 cases lost follow-up. The remaining cases were divided into the restenosis (n=16) and non-restenosis (n=84) group according to their coronary angiography result. Plasma levels of ET-1 and P-selectin reached the peak concentration in the two groups right after PCI. In the non-restenosis group, plasma levels of ET-1 and P-selectin resumed to pre-opeation level at 24 hours and resumed to normal level at 2 weeks. In the restenosis group, plasma levels of ET-1 and P-selectin did not resume to normal level at 2 weeks but increased persistently, and showed their second peak value at 3-6 months after PCI. Conclusion The risk of restenosis increased accompanied by the persistent increase of plasma levels of ET-1 and P-selectin in early stages (1-2 weeks) after PCI in ACS patients. ET-1 and P-selectin may be regarded as makers for early recognition of restenosis.