The pathophysiologic basis for potent platelet inhibition in the acute coronary syndromes has been established. In the setting of PTCA for unstable angina and non-Q-wave myocardial infarction, there are clear data for a benefit of GP IIb/IIIa inhibition, whereas for primary PTCA in evolving myocardial infarction, preliminary data are very encouraging and a large-scale clinical trial is nearly completed. Glycoprotein IIb/IIIa inhibition as an adjunct to medical therapy for unstable angina is also the subject of encouraging preliminary data, and 3 large-scale clinical trials have just been completed. Preliminary data have also been accrued for GP IIb/IIIa inhibition as conjunctive therapy with thrombolytic agents, and large clinical trials are now commencing.