Background: Coronary vessel dominance, defined by the coronary artery that supplies the posterior descending artery (PDA) and posterolateral branches, influences the relative contribution of the different coronary arteries to the total left ventricular blood flow. This work aimed to evaluate the prognostic value of coronary arterial dominance post primary PCI, during hospital stay and at 3-month follow-up, which include; cardiac mortality, heart failure, non-fatal myocardial infarction, re-vascularization, stroke/TIA and re-admission for ACS. Methods: This prospective observational study included 100 patients a with STEMI who underwent successful primary percutaneous coronary intervention with TIMI III flow and without procedural complications. Patients were divided into 3 groups according to coronary dominance: Right coronary dominant group (RCD), left coronary dominant group (LCD) and balanced coronary dominant group (BCD). All patients were subjected to transthoracic echocardiogram and coronary angiography and Primary percutaneous coronary intervention. Results: Ticagrelor and clopidogrel during hospital stay and on hospital discharge were significantly used more with RCA group than LCX group and LCX & RCA group (P=0.021, 0.012), (P=0.018, 0.014), respectively. GPIIB/IIIA was significantly more used during hospital stay with RCA group than LCX group and LCX & RCA group(P=0.014). Nitrates was significantly used more on hospital discharge with RCA group than LCX group and LCX & RCA group (P<0.001). Conclusions: Coronary arterial domi¬nance showed significant prognostic value in cases of myocardial Infarction after PCI, heart failure in LCX cases and in revascularization, heart failure, and stroke/TIA cases in RCA. Further, readmission for ACS was the most common outcome in all groups after 3-months follow-up.