In their recent ‘Therapeutic Perspective’ published in Clinical Investigation, Elwood and colleagues present their therapeutic perspective on the risks and benefits of prophylactic aspirin in vascular disease and cancer [1]. Nobody would disagree with the clinical implications of the cogent evidence in the secondary prevention of vascular diseases that aspirin reduces subsequent myocardial infarction (MI), stroke and cardiovascular (CV) death in a wide range of survivors of prior occlusive vascular disease events. These include survivors of prior MI, stable and unstable angina, occlusive stroke, transient ischaemic attacks, coronary artery bypass graft surgery, and percutaneous coronary interventions with and without stents. In all these highrisk subjects, the relative-risk reduction of approximately a quarter corresponds to an absolute risk-reduction of approximately ten to 20 important vascular events per 1000 people and to a smaller, but still definite, reduction in vascular death [2]. In all these high-risk patients, the absolute benefits of aspirin on important vascular events far exceed, by approximately tenfold, the absolute risks of major gastrointestinal or other major extracranial bleeds. Such cogent evidence is also available among even higher-risk patients undergoing acute MI, as well as acute occlusive stroke. Since their absolute risks of MI, stroke and vascular death are even higher than among survivors of prior occlusive vascular events, their absolute benefits from aspirin are even greater. in which the absolute benefits of aspirin are even greater than among longer-term survivors of prior occlusive vascular events. Thus, the absolute benefits of aspirin are far greater than the absolute risks in acute MI or occlusive stroke, as well as in the secondary prevention of CV disease. In primary prevention, however, the balance is less clear. This situation is due, at least in part, to the fact that in apparently healthy subjects without prior evidence of clinical CV disease, their absolute risks of a first event and, as a consequence, the absolute benefits of aspirin are generally approximately tenfold lower than in secondary prevention patients receiving aspirin [3]. In primary prevention of vascular diseases, aspirin produces a conclusive and statistically significant reduction in the risk of a first MI. Nonetheless, there is substantial disagreement regarding whether this reduction clearly outweighs the bleeding risks in the low-risk individuals with no history of CV disease who have been randomized in the trials [4]. Several reputable, international organizations, including one in the UK [5] and one in the USA [6], have issued general guidelines for the use of aspirin in the primary prevention of a first MI. In most of these guidelines, aspirin is recommended for apparently healthy subjects whose absolute risk of a first coronary event is thought to exceed the absolute risk of major extracranial bleeding due to aspirin. In some “...any judgments about prescribing long-term aspirin therapy for apparently healthy individuals ... should be based on individual clinical judgments between the doctor and each of his or her patients...”