Objectives: We sought to investigate whether GPI used during PCI in patients with acute MI complicated by cardiogenic shock (CS) would improve clinical outcome. Background: The efficacy of glycoprotein IIb/IIa receptor inhibitors (GPI) during percutaneous coronary intervention (PCI) for acute myocardial infarction (MI) has recently been challenged. Methods: A total of 701 patients with CS from the Korea Acute Myocardial Infarction Registry and Korea Working Group on Myocardial Infarction Registry were divided into 2 groups: patients receiving GPI (n = 164) and those not receiving GPI (n = 537) at the time of PCI for acute MI. Twelve-month clinical outcome after PCI were compared between the groups. Propensity score analysis was used to control for potential confounders. Results: Patients receiving GPI more often had ST-elevation MI (92.7% vs. 81.8%, P=0.001), left main coronary artery disease (12.8% vs. 4.3%, P<0.001), lesion type B2C (78.0% vs. 67.2%, P=0.008), lower rates of pre-PCI Thrombolysis In Myocardial Infarction flow 3 (6.1% vs. 16.6%, P=0.001) and drug-eluting stenting (74.4% vs. 81.9%, P=0.034). They were more likely to receive cardiopulmonary resuscitation (31.1% vs. 19.6%, P=0.002), mechanical ventilation (37.8% vs. 28.9%, P=0.030), and anticoagulation with unfractionated heparin (72.0% vs. 56.1%, P<0.001). Comparison between 155 patients receiving GPI and 155 propensity-matched patients not receiving GPI found no statistical differences in major bleeding (2.6% vs. 1.9%), in-hospital mortality (22.6% vs. 29.0%), 1-month mortality (24.5% vs. 32.3%), or rates of death (26.5% vs. 34.8%; HR, 0.75; 95% CI, 0.48 to 1.15; P=0.192) and death/MI (29.0% vs. 35.5%; HR, 0.77; 95% CI, 0.50 to 1.18; P=0.234) at 12 months after PCI. Conclusions: GPI administered during PCI failed to improve clinical outcome in patients with acute MI complicated by CS.