Abstract Background Myocardial infarction (MI) clinical presentation and prognosis usually vary between men and women. Studying different age groups may be of interest. Aim Compare clinical characteristics and prognosis between men and women under 65 years old (y/o) with MI. Methods observational prospective study, including all patients admitted for MI between 2016 and 2023. Median follow-up was 43months[20-71]. Results Out of a total of 1064 patients, 436 were younger than 65 y/o (98 were women and 338 were men). The median age was similar in both sexes: 53.4[41-65] vs 54.2[43-65], p=0.24. A higher percentage of men were married (76.6 vs 59.2%, p<0.01), while a greater proportion of women were widowed (7.9 vs 1.3%, p<0.01). Men showed higher rates of permanent employment (71.4vs54.9%, p=0.01) and night shifts (58vs26.1%, p<0.01), whereas women had a higher unemployment rate (26.8vs15.2%, p=0.03) and reported higher levels of stress (70.3 vs 42.4%, p<0.01). The percentage of smokers was similar in both sexes (84.6% in men vs 75.8% in women, p=0.06), but there were more cocaine users in the male group (10.8vs1.4%, p=0.01). Women had a higher prevalence of autoimmune diseases (20.4 vs 6.2%, p<0.01), allergies (17.3 vs 5.6%, p<0.01), psychiatric illnesses (25.8 vs 9.9%, p<0.01), and migraines (15.6 vs 1.8%, p<0.01). Men had more history of previous coronary angioplasty (9.5 vs 3.1%, p=0.05). At admission, men presented with higher levels of creatine kinase (1175.2±1490.1 vs 766.5±1084.5 U/L, p=0.02), haemoglobin (15.2±1.6 vs 14±1.4 g/dl, p<0.01) and serum creatinine (1.2±1.4 vs 0.8±0.5 mg/dl, p<0.01), while women exhibited higher cholesterol levels (186.5±51.6 vs 174.9±44.5 mg/dl, p=0.03). Coronary dissection and myocardial infarction with non-obstructive coronary arteries were more frequent in women (14.3 vs 2.1%, p<0.01 and 27.6 vs 11.5%, p<0.01, respectively). Women also underwent additional tests at a higher rate, such as cardiac magnetic resonance (14.3 vs 4%, p<0.01) and vasospasm test (7.6vs1.9%, p=0.02). During hospitalization, men underwent drug-eluting stent implantation more frequently (66.7vs23.8%, p<0.01). At discharge, they were more likely to receive antiplateles (93.7vs84.5%, p<0.01), beta-blockers (81.7vs.71.1%, p=0.03), angiotensin-converting enzyme inhibitors (63.2vs49.5%, p=0.02) and statins (96.4vs84.5%, p<0.01). The rest of variables, which showed no significant differences, are in Table 1. Prognosis was similar in both sexes: death from any cause (HR 0.7, 95%CI[0.1-3.4]), cardiovascular readmission (HR 1.2, 95%CI[0.5-2.7]), reinfarction (HR 1.9, 95%CI[0.3-10.3]), stroke (HR 1, 95%CI[0.1-11.9]). Conclusion The clinical profile of men and women with MI is clearly different. The investigation into the underlying mechanisms of MI occasionally necessitates more extensive testing in women. Additionally, the treatment plans at discharge diverge between the two genders. Nevertheless, the prognosis appears to be similar for both sexes.