[Cardiology.  Platelet function testing for clinicians]. 
Platelet P2YI2 receptor inhibition with clopidogrel, prasugrel or ticagrelor plays a key role to prevent recurrent ischaemic events after percutaneous coronary intervention in acute coronary syndromes or elective settings.  The degree of platelet inhibition depends on the antiplatelet medication used and is influenced by clinical and genetic factors.  A concept of therapeutic window exists.  On one side, efficient anti-aggregation is required in order to reduce cardio-vascular events.  On the other side, an excessive platelet inhibition represents a risk of bleeding complications.  This article describes the current knowledge about some platelet function tests and genetic tests and summarises their role in the clinical practice.