Myocardial infarction (MI) is relatively rare in young patients. Atherosclerosis is responsible for most cases, but in one fifth of reported events other causes of MI are involved. Regarding individual susceptibility, it seems that cigarette smoking is the most common modifiable risk factor; family history and lipid abnormalities can also play an important role. In the absence of obvious risk factors a careful search for other contributing factors (such as vasospasm, vasculitis, cardiac masses or hypercoagulable states) is warranted.