Efficacy, safety, and cost will determine the use of glycoprotein IIb/IIIa therapy in patients with acute coronary syndromes or those patients undergoing percutaneous coronary intervention (PCI). Prospective randomized studies with abciximab, eptifibatide, and tirofiban have demonstrated the superior efficacy and relative safety of IIb/IIIa therapy in these 2 broad patient groups. In medical practice, we by necessity make decisions to administer or withhold therapies based on implicit concepts of cost- effectiveness and efficacy and safety. We herein review available economic data on IIb/IIIa therapy to assist in this decision-making process. The procurement costs of the IIb/IIIa receptor antagonists vary considerably for both acute coronary syndrome and patients undergoing PCI. In PCI, these procurement costs range from $436 to $1407 per patient treated with commonly used regimens. Economic substudies of PCI trials with abciximab and tirofiban demonstrate medical cost savings that partially offset drug procurement costs. The number of dollars spent on IIb/IIIa agents per death or myocardial infarction prevented in patients undergoing PCI ranges from $13,000 to $37,000. Abciximab has cost-effectiveness ratios of $4000 to $7000 per life- year saved in patients undergoing PCI. The incremental cost-effectiveness of IIb/IIIa blockade in the setting of planned stenting is unknown. In patients with acute coronary syndrome, procurement costs range from $1050 to $1548 per patient treated. Expenditures per death or myocardial infarction prevented in patients with acute coronary syndrome range from $32,000 to $82,000. Inadequate direct cost data exist to calculate cost effectiveness ratios for this group, but only high-risk patients will likely have cost-effectiveness ratios that most Western health-care systems can afford.