Percutaneous coronary interventions (PCIs) with intravenous platelet glycoprotein (GP) IIb/IIIa receptor inhibitors have become the standard of care within the higherrisk population of patients with acute coronary syndromes. Three U.S. Food and Drug Administration–approved GP IIb/IIIa inhibitors are available in the marketplace—abciximab (ReoPro), tirofiban (Aggrastat), and eptifibatide (Integrelin)— and a fourth remains in clinical trials (lamifiban). The existence of a “class effect” among all the GP IIb/IIIa receptor inhibitors is hotly debated, but the variance of effectiveness seen even among the small-molecule drugs argues against the “class effect." In patients with acute coronary syndromes, the superiority of the large molecule, abciximab, over the small molecule, tirofiban, has been shown. In diabetic patients with acute coronary syndromes, abciximab is the only GP IIb/IIIa receptor inhibitor to provide a significant mortality advantage in patients undergoing PCI. Abciximab is also the only agent where clinical data support safety in patients with chronic renal insufficiency.