Objective To investigate the relationship between serum cystatin C (Cys C) level and the occurrence of in-stent restenosis after coronary drug-eluting stent implantation.Methods A retrospective analysis of coronary drug-eluting stent implantation was curried out in 592 patients.All patients were from Shengjing Hospital of China Medical University by coronary angiography,and were divided into restenosis group (142 cases) and non restenosis group (450 cases).The Cys C levels before and after surgery and follow-up angiography were analyzed.The biochemical indicators,and transcatheter arterial restenosis were analyzed.Results Either before or after operation and follow-up angiography,serum cystatin C levels were higher in restenosis group patients than that in non restenosis group [before operation:(1.622 ± 1.063) mg/L vs (1.369 ± 0.860) mg/L;after the operation:(1.769 ± 1.062) mg/L vs (1.458 ± 0.883) mg/L;review:(1.924 ± 1.085) mg/L vs (1.440 ± 0.874) mg/L;P ＜ 0.05].Multivariate COX regression analysis showed that serum cystatin C level was an independent risk factor of in-stent restenosis in drugeluting area (P ＜ 0.05).Conclusions The serum cystatin C level is closely related to in-stent restenosis in drug-eluting stents area.High level of serum cystatin C is an independent risk factor of in-stent restenosis after drug-eluting stents implantation.