Aspirin is prescribed in almost all coronary patients. However, the prescription modalities tend to vary, partly because of the absence of phase II development of this molecule as an antithrombotic agent in coronary patients. The dose of 162.5 mg has been shown to be effective during the acute phase of myocardial infarction, but we do not know whether this is the most effective dose. A higher dose, in particular 500 mg to 1 g, would have the advantage of more rapidly and more completely blocking platelets during an acute thrombotic phase. After this first high dose, lower doses, less than 100 mg, could be administered in the long term. These low doses of aspirin, generally 75 mg, have been demonstrated, in stable angina, to decrease infarction and sudden death by more than 30%. This dose has also been demonstrated to be effective in the long-term in unstable angina, but once again this low dose should be introduced after an initial higher dose for this acute coronary syndrome. A primary prevention study is currently underway using the dose of 75 mg per day following the trial in American physicians using a dose of 320 mg every second day. Long-term low doses have a clearly demonstrated efficacy in chronic prevention and have the advantage of inducing much fewer adverse effects, particularly gastrointestinal haemorrhage. In conclusion, a high initial dose should be recommended in acute coronary syndromes and a low dose, less than 100 mg, should be recommended for chronic prevention. Buffered forms, protecting the stomach, and sustained-release forms are impatiently awaited to further improve the benefit/risk ratio of aspirin, which is nevertheless already excellent.