Objective:To investigate the role of serum CX3CR1 in the diagnosis of coronary artery stenosis and in the evaluation of prognosis after percutaneous coronary intervention.Methods:A total of 101 patients with coronary artery stenosis (≥ 50% stenosis) confirmed with coronary angiography (CAG) in Haiyang People's Hospital from January 2018 to May 2019 who were followed up till May 2021 were included in the observation group. Thirty-four healthy individuals who underwent physical examination during the same period were included in the control group. Patients in the observation group were divided into an in-stent restenosis group (ISR group, n = 28) and a non-ISR group ( n = 73). The expression of CX3CR1 was detected. The incidence of adverse cardiac events was calculated. The sensitivity, specificity, and area under the curve (AUC) plotted for the use of CX3CR1 to diagnose coronary artery stenosis and predict adverse cardiac events were evaluated. Results:The expression of CX3CR1 in the observation group was (3.95 ± 1.05) μg/L, which was significantly higher than (2.30 ± 0.65) μg/L in the control group ( t = 2.87, P < 0.05). The receiver operating characteristic curve analysis showed that the AUC, sensitivity, and specificity of the use of CX3CR1 in diagnosing coronary artery stenosis were 0.892, 75.2%, and 88.2%. The incidence of non-fatal myocardial infarction, angina pectoris, heart failure, and cardiac death in the ISR group was significantly higher compared with the non-ISR group ( χ2 = 8.06, 7.17, 8.06, 7.17, all P < 0.05). The receiver operating characteristic curve analysis results showed that the AUC value of CX3CR1 in predicting non-fatal myocardial infarction, angina pectoris, heart failure, and cardiac death were 0.786, 0.895, 0.997, and 0.887, respectively. Conclusion:CX3CR1 is highly expressed in coronary artery stenosis, which can provide a reference for the diagnosis and prognostic evaluation of coronary artery stenosis.