Antiplatelet drugs belong to the class of pharmaceuticals that inhibit platelet activation and thereby suppress arterial thrombus formation. They are widely used for primary and secondary prevention of atherothrombotic diseases including coronary heart diseases, ischemic strokes and peripheral arterial diseases. These drugs are broadly classified into two categories: (1) inhibitors of the platelet activation signal-transduction system, and (2) stimulators of production of inhibitory signals such as cAMP and cGMP. The first category comprises ADP receptor (P2Y₁₂) antagonists including ticlopidine, clopidogrel and prasugrel; the serotonin 5-HT₂ receptor antagonist sarpogrelate; the cyclooxygenase-1 inhibitor aspirin; and eicosapentaenoic acid. The second category comprises prostacyclin analog, the cyclic nucleotide phosphodiesterase (PDE)-3 inhibitor cilostazol, and the PDE-5 inhibitor dipyridamole. Drugs in the second category stimulate vasodilation, as well as inhibit platelet aggregation. Current clinical trial evidence favors the use of aspirin, clopidogrel and cilostazol as first-line agents in the majority of patients with vascular disease. Clinical trials evaluating novel antiplatelet drugs will impact the direction of future practice.