OBJECTIVES: To compare the use of guideline-recommended medical and interventional therapies in older and younger patients with acute coronary syndromes (ACSs). DESIGN: Prospective cohort study. SETTING: Fifty-five hospitals in Switzerland. PARTICIPANTS: Eleven thousand nine hundred thirty-two patients with ACS enrolled between March 1, 2001, and June 30, 2006. ACS definition included ST-segment elevation myocardial infarction (STEMI), non-ST-segment elevation myocardial infarction (NSTEMI), and unstable angina pectoris (UA). MEASUREMENTS: Use of medical and interventional therapies was determined after exclusion of patients with contraindications and after adjustment for comorbidities. Multivariate logistic regression models were used to calculate odds ratios (ORs) per year increase in age. RESULTS: Elderly patients were less likely to receive acetylsalicylic acid (OR=0.976, 95% confidence interval (CI)=0.969-0.980) or beta-blockers (OR=0.985, 95% CI=0.981-0.989). No age-dependent difference was found for heparin use. Elderly patients with STEMI were less likely to receive percutaneous coronary intervention (PCI) or thrombolysis (OR=0.955, 95% CI=0.949-0.961). Elderly patients with NSTEMI or UA less often underwent PCI (OR=0.943, 95% CI=0.937-0.949). CONCLUSION: Elderly patients across the whole spectrum of ACS were less likely to receive guideline-recommended therapies, even after adequate adjustment for comorbidities. Prognosis of elderly patients with ACS may be improved by increasing adherence to guideline-recommended medical and interventional therapies.