Background: Tricuspid regurgitation (TR) is associated with adverse prognosis in various patient populations but currently no data is available about the prevalence and prognostic implication of TR in ST-segment elevation myocardial infarction (STEMI) patients. We investigated the possible implication of TR among STEMI patients. Methods: We conducted a retrospective study of STEMI patients undergoing primary percutaneous coronary intervention (PCI), and its relation to major clinical and echocardiographic parameters. Patients records were assessed for the prevalence and severity of TR, its relation to the clinical profile, key echocardiographic parameters, in-hospital outcomes, and long-term mortality. Patients with previous myocardial infarction or known previous TR were excluded. Results: The study included 1071 STEMI patients admitted between September 2011 and May 2016 (age 61 ± 13 years; predominantly male). A total of 205 patients (19%) had mild TR while another 32 (3%) had moderate or greater TR was 3% (n = 32). Patients with significant TR demonstrated worse echocardiographic parameters, more likely to have in-hospital complications and had higher long-term mortality (28% vs. 6%; p<0.001). Following adjustment for significant clinical and echocardiographic parameters, mortality hazard ratio (HR) of at least moderate to severe TR remained significant (2.44; 95% CI, 1.06-5.6; P = .036) for patients with moderate-severe TR. Conclusions: Among STEMI patients after primary PCI, the presence of moderate-severe TR was independently associated with adverse outcomes and significantly lower survival rate. Keywords: Tricuspid Regurgitation; ST-segment elevation myocardial infarction; percutaneous coronary intervention; cardiac intensive care unit; cardiac intensive care unit; echocardiography; valvular regurgitation.