Aspirin is a cornerstone in the prevention of ischemic events and guidelines usually recommend a once-daily dosing. This dosing is based at least in part on the platelet renewal rate, which is of only 10-15% a day. A once-daily dosing is now challenged by several studies demonstrating that when platelet turnover is increased, such as in patients with diabetes or essential thrombocytemia, the inhibition of platelet function provided by aspirin is no longer homogeneous between dosing with a significant recovery of platelet function within a day that is blunted by a twice-daily dosing. This review addresses the issue of aspirin dosing in selected patients in the controversial era of personalized antiplatelet therapy.