BACKGROUND: Coronary heart disease (CHD), the leading cause of death in the United States, accounted for approximately 490,000 deaths in 1993. Angina pectoris, a manifestation of CHD, accounted for 13,586 Medicare discharges in 1993 in Texas. A pilot project showed aspirin prophylaxis that reduces cardiovascular morbidity and mortality in individuals with acute angina is underused. Texas Medical Foundation collaborated with 10 acute-care facilities to improve aspirin prophylaxis. METHODS: Collaborators assessed processes of care and implemented clinical pathways to improve aspirin administration. Data were abstracted from medical records before and after pathway implementation to evaluate impact. RESULTS: Aspirin administration during hospital stay increased 10.8%, aspirin administration on discharge increased 11.7%, and average time from arrival to aspirin administration decreased 2.9 hours. CONCLUSIONS: Results suggest collaborator-implemented clinical pathways significantly improved care received by Medicare patients admitted for cardiac-related acute chest pain/angina. Data suggest room for further improvement.