Although present in pharmacotherapy for more than 100 years, aspirin still represents a cornerstone in the primary and secondary prevention of cardiovascular patients. Despite undoubtful benefit, a certain proportion of patients treated with aspirin develops adverse atherothrombotic events like stent thrombosis, myocardial infarction, stroke and cardiovascular death. In recent years, there is a growing scientific interest concerning the relationship of suboptimal antiplatelet response to aspirin and cardiovascular prognosis that has led to the concept of "aspirin resistance". Besides the absence of uniform definition of aspirin resistance, an important issue in these studies are numerous and poorly standardized laboratory methods that are used in its detection. Despite an increasing number of reports that favour its clinical significance, there are still no expert recommendations for routine assessment of platelet aggregation as well as for modification of antiplatelet doses or regimens in the case of established aspirin resistance.