Platelet activation following the erosion or rupture of an atherosclerotic plaque is central to the development of acute coronary syndromes (ACS). Inhibition of the final common pathway of platelet aggregation using glycoprotein (GP) IIb/IIIa inhibitors has been evaluated in large-scale trials of patients with ACS. There is now consistent evidence across several trials using different parenteral GP IIb/IIIa inhibitors of improved outcomes for ACS patients treated with these agents both as primary treatment and as an adjunct to coronary intervention. The benefits particularly relate to high-risk patients. In contrast oral GP IIb/IIIa inhibitors have not been shown to improve outcomes in ACS patients.