Although myocardial infarction (MI) mainly occurs in patients older than 45, young men or women can suffer MI. Fortunately, its incidence is not common in patients younger than 45 years. However, the disease carries a significant morbidity, psychological effects, and financial constraints for the person and the family when it occurs at a young age. The causes of MI among patients aged less than 45 can be divided into four groups: (1) atheromatous coronary artery disease; (2) non-atheromatous coronary artery disease; (2) hyper-coagulable states; (4) MI related to substance misuse. There is a considerable overlap between all the groups. This article reviews the literature and highlights the practical issues involved in the management of young adults with MI.