Multiple studies have demonstrated that subgroups of patients receiving combination therapy with aspirin and clopidogrel fail to produce the anticipated antiplatelet effect, and various terms such as 'aspirin resistance', 'clopidogrel resistance', 'heightened post-treatment platelet reactivity' and 'residual platelet reactivity' have been introduced in the medical literature. Light transmittance aggregometry is generally considered to be the gold standard for determining platelet function, but its relevance to in vivo platelet function is questionable and the logistical demands of the method make it impossible to use in daily practice. The introduction of several point-of-care platelet function assays may be the key to the widespread clinical use of platelet function testing and may identify patients who are at risk for the occurrence of adverse cardiac events. In the present paper, we discuss the current commercially available methods of assaying platelet function, including their advantages and limitations and whether they have been shown to correlate with clinical outcomes.