Abstract: Objective: To observe the change of heart rate variability(HRV) in patients with coronary artery disease(CAD) before and after percutaneous coronary intervention(PCI) and to evaluate the prognosis of CAD patients receiving PCI.Methods: Thirty-two PCI patients confirmed by coronary arteriography and suitable to PCI were divided into angina pectoris group(20 cases) and myocardial infarction group(12 cases).The time-domain(SDNN,SDANN,rMSSD,PNN50) and frequency-domain(LF,HF) of HRV were analyzed before PCI and one month,six months after PCI.Results: There was a significant improvement of SDNN,SDANN and HF(P<0.01) one month after PCI,and more improvement was observed in other indices(P<0.01) except rMSSD(P>0.05)six months after PCI.Conclusions: HRV in patients with CAD can be improved significantly after PCI,and it may be related to the improvement of myocardial circulation,and the correction of the dysfunction of sinus node and myocardium due to the unbalance of neuro-humoral factors.