Background: We sought to assess the feasibility and outcome of primary percutaneous coronary intervention (PCI) for ST-segment elevation myocardial infarction (STEMI). Methods: Between April 2014 and April 2015, consecutive STEMI patients who underwent primary PCI were prospectively enrolled in a primary PCI registry. The patients’ demographics, risk factors, procedural characteristics, and in-hospital and 6-month major adverse cardiac events (MACE) were assessed. Results: A total of 393 patients underwent primary PCI during this period. The mean age was 58±11 years and 80.6% were male. Additionally, 40.7% of the patients were hypertensive, 37.9% had dyslipidemia, 37.7% were smokers, and 29% had diabetes mellitus. Single-vessel disease was found in 36.6% of the study population, 2-vessel disease in 30.5%, and multivessel disease in 27.7%. At admission, 74.5% of the patients had TIMI grade 0 flow. Following revascularization, 74.7% achieved TIMI grade 3 flow, 22% TIMI grade 2 flow, and 1.8% TIMI grade 1 flow—as 1.5% had TIMI grade 0 flow. The predictors of the TIMI flow grade after primary PCI included history of diabetes mellitus, lesion severity, time elapsed symptom onset to admission, and use of thrombectomy. Stent thrombosis developed in 5.6% of the patients; it was more frequent among those receiving bare-metal stents. The in-hospital and 6-month mortality rates were 5.9% and 2.3%, correspondingly. In-hospital mortality was strongly related to the TIMI flow grade. Conclusions: Our study demonstrated that the outcome of primary PCI was strongly related to the postprocedural TIMI flow grade. Patients with lower TIMI flow grades postprocedurally should receive special attention. (Iranian Heart Journal 2016; 17(3):6-11)