Objective To evaluate role of intracoronary electrocardiogram (IcECG) in examining early myocardial damage during elective percutaneous coronary intervention (PCI). Methods Eighty-six patients of coronary heart disease with normal serum levels of creatine kinase-myoglobin (CK-MB) and cardiac troponin T (cTnT) before the procedure and undergone elective PCI were enrolled in the study.Their IcECG were recorded by a intracoronary guidewire and serum levels of CK-MB and cTnT were measured at baseline and eight and 24 hours after the procedure, respectively. The patients were divided into two group, abnormal and control, according to whether they had significant shift at ST-segment in IcECG.Cardiac events after intervention in the patients were followed-up and recorded. Myocardial damage was defined as serum level of cTnT increased to above the upper normal value after intervention. Results Significant shift at ST-segment in IcECG during PCI in 30 (35%, abnormal group) and no shift in other 56patients (65%, control group) of 86 patients with normal serum levels of cardiac markers before the procedure was observed, and all the procedure were successful Serum levels of cTuT and CK-MB significantly increased after intervention in 30 patients of abnormal group than those in control one ( P <0. 01 ). Sensitivity of intracoronary ST-segment shift was 77 percent for predicting myocardial damage, and specificity was 94 percent, with positive and negative predictive values of 90 percent and 86 percent,respectively. More cardiac events were observed at 4-week follow-up after intervention in abnormal group than those in control one (P<0. 05) and major coronary event-free survival was significantly lower in those with post-procedural ST-segment elevation in IeECG (P < 0. 05). Conclusions ST-segment shift in IcECG may be helpful for predicting myocardial damage during PCI procedure on time.