Over recent years, substantial clinical trial evidence regarding glycoprotein IIb/IIIa inhibition for the medical management of non-ST segment elevation acute coronary syndromes has been compiled. Despite being recently advocated for the management of coronary instability within widely accepted guidelines, its use among patients presenting with acute coronary syndromes remains somewhat contentious. Within randomized placebo-controlled trials, uniform efficacy with the glycoprotein IIb/IIIa inhibitors has not been shown, whereas a disturbing excess in adverse events is evident within some trials. Currently, the basis for this heterogeneity of clinical evidence has not been adequately explained. However, evolving insights from clinical trials and basic research have further refined our understanding of glycoprotein IIb/IIIa antagonist therapy and the potential effects beyond the inhibition of the fibrinogen receptor. Likewise, appreciation of the pharmacokinetic characteristics of these agents provides putative explanations for the diverse findings of the randomized trials. Reexamination of the clinical trial data in light of this recent evidence provides a basis for interpreting the marginal results of glycoprotein IIb/IIIa inhibition in acute coronary syndromes. Consideration of these factors may facilitate the optimal clinical application of this class of agents to the management of coronary instability.