Background: Diabetes is the cause of 25% of all the cases of coronary artery disease and myocardial infarction (MI). One of the best interventions for coronary artery occlusion treatment is percutaneous coronary intervention (PCI). In PCI, myocardial area size, lesion morphology, cardiac function, renal failure, and other comorbidities are very important. Evaluation of the periprocedural MI prevalence is significant for comparing diabetic and nondiabetic patients. Methods: This cross-sectional study was done in Rajaie Cardiovascular, Medical, and Research Center by convenience sampling in 2009. PCI was performed on 605 patients, comprising 171 diabetic and 434 nondiabetic patients. Our information form included the type of contrast, arterial access, diabetic type, blood glucose control, lab tests, and number of coronary artery lesions. The incidence of postprocedural MI was evaluated by the measurement of CK-MB. The data were then entered into SPSS before they were described and analyzed. The χ2 test and the t-test were employed for data evaluation. Results: The incidence of post procedural MI was 2.9% in the diabetics and 2.5% in the nondiabetics. Moreover, 71.7 % of the patients were diabetic and 28.3% were nondiabetic. The blood glucose level was controlled in 12.6% of the study population, while it was not controlled in 87.4%. The P value for the comparison of periprocedural MI between the diabetic and nondiabetic patients was 0.788. All of the 5 diabetic patients with periprocedural MI belonged to the uncontrolled blood glucose group. The highest frequency of MI was in the patients with 3-vessel PCI (P=0.027). Conclusions: No significant statistical difference was observed regarding postprocedural MI between the diabetic and nondiabetic patients. Preprocedural MI was more frequent in the patients with 3-vessel PCI. PCI is a safe procedure with a low incidence rate of postprocedural MI. (Iranian Heart Journal 2017; 18(2):36-42)