Objective To determine the effect of antiplatelet drugs efficiency evaluated by thromboelastography on in-stent restenosis (ISR) in the patients after percutaneous coronary intervention (PCI). Methods A retrospective analysis was carried out on the patients undergoing successful coronary stenting and then coming back for angiography at Heart Center in Air Force General Hospital from September 2011 to June 2014. These patients were defined as ISR group and non-ISR group according to the results of coronary angiography. The possible factors that led to ISR were analyzed and compared between the 2 groups. Results There were a total of 86 patients with 118 drug-eluting stents implanted recruited in this study. ISR was found in 20 patients. There were significant differences in the lesion length [(27.20±3.19) vs (22.94±4.67)mm], the serum level of C-reactive protein [CRP, (6.36±2.69) vs (3.14±3.23)mg/L], the inhibitory rates of arachidonic acid (AA) pathway [(68.54±17.63) vs (78.59±20.39)] and adenosine 5￠-diphosphate (ADP) receptor [(35.80±15.58) vs (60.31±20.91)], the ratio of diabetes patients and the manifestations between the 2 groups (P＜0.05). Multivariate logistic regression analysis indicated that the lower inhibitory rate of ADP receptor was a risk factor of ISR (P＝0.011) after adjustment for other risk factors. Conclusion The inhibitory rate to ADP receptor is negatively related to ISR, indicating that hyporesponsiveness of clopidogrel plays an important role in the pathogenesis of ISR.