In patients with acute coronary syndromes not undergoing revascularisation, it is important to decrease ischemic and bleeding complications. TRILOGY-ACS study randomised patients with non-ST elevation acute coronary syndromes not undergoing revascularisation to clopidogrel or prasugrel. The primary endpoint of 30 day cardiovascular death, myocardial infarction or stroke was not different between the two groups in a median follow up of 17 months. A prespecified subgroup analysis showed that the subgroup with angiographically confirmed coronary artery disease benefited from prasugrel more. It was also shown that titrating dose according to patient characteristics decreased bleeding. To clarify the optimal timing of thienopyridine administration, ACCOAST study compared the effects of prasugrel administration at the time of diagnosis and after angiography in patients with non-ST elevation acute coronary syndromes. Prasugrel pretreatment did not decrease the 30-day rate of major ischemic events but increased major bleeding in patients with non-ST elevation acute coronary syndromes and those undergoing catheterization. These results support the guidelines recommending prasugrel administration after the coronary anatomy is defined.