Background Coronary artery disease (CAD) is the commonest cause of death worldwide. ST-segment elevation myocardial infarction (STEMI) and its consequences can be devastating particularly at younger age for a bigger impact on the patient’s psychology and ability to work. Little is known about the differential features and outcomes of young STEMI patients in Egypt. This study characterized young STEMI patients (≤ 45 years) compared to patients > 45 years and evaluated 1-year outcomes. Results A total of 492 eligible STEMI patients who presented to the National Heart Institute and Cairo University Hospitals were recruited. Young STEMI patients (< 45 years old) represented 20% of all STEMI comers. Male gender was predominant in both groups, yet with a significantly higher proportion in the younger compared to older patients (87% vs. 73%, p = 0.004). Compared to older patients, young STEMI patients had characteristically higher rates of smoking (72.4% vs. 49.7%, p < 0.001) and family history (13.3% vs. 4.8%, p = 0.002), while significantly lower rate of other conventional CAD risk factors as diabetes, hypertension, and dyslipidemia (20.4% vs. 44.7%, 20.4% vs. 44.9% and 12.7% vs. 21.8%, respectively, p < 0.05 for all). Follow-up was continued for at least 12 months after the index event. Younger STEMI patients had fewer major adverse cardiovascular events and fewer heart failure hospitalizations compared to the older controls (10.2 vs. 23.9% and 18.4% vs. 34.8%, respectively, p < 0.005 for both), however, 1-year mortality was similar (3.1% vs. 4.1%, p = 0.64). Conclusions Younger STEMI patients (≤ 45 years) show peculiar characteristics, with significantly higher rates of smoking and family history of premature CAD, while less prevalence of other conventional CAD risk factors. Overall MACE occurred less in younger STEMI patients; however, the mortality rate was similar to the older controls.