Anti-platelet drugs play a key role in cardiovascular medicine since the introduction of aspirin as an anti-thrombotic agent some 50 years ago. After many years of a "monopoly" of aspirin, ADP receptor P2Y12 inhibitors were introduced with a significant improvement in clinical outcome. Nowadays dual anti-platelet therapy is the common practice for both acute events and secondary prevention in selected groups of patients. The improved efficacy of multiple drug therapy is associated with an increased risk of bleeding, which raises the issue of the dosing of these drugs. Recently, numerous studies have reported a variable laboratory response to aspirin and clopidogrel, which correlates with clinical outcome. Several mechanisms for causing this variable response have been proposed, including genetic variability, disease burden, and others. A major obstacle in this field is the lack of a standardized method for testing these responses. New drugs are currently under different stages of development, including new P2Y12 receptors inhibitors, thrombaxane receptor blockers, direct thrombin inhibitors, and inhibitors for other signaling pathways including oral GPIIbIIIa inhibitors. Thus anti-platelet therapy is currently under intensive developments toward multiple drug therapy and personal dose adjustment, which may improve clinical outcome.