.Whilst there is increasing realization that inappropri-ate platelet activation plays a prime role in the increas-ing heart disease burden of society, there is still nogenerally accepted ideal measure of platelet activationthat would indicate a state of ‘high risk’. There is also aneed for the objective assessment of the relative effec-tiveness and safety of antiplatelet agents. Furthermore,despite the great success of aspirin, it is clearly far fromperfect