BACKGROUND: The rapid expansion of managed care in the United States has increased debate regarding the appropriate mix of generalist and specialist involvement in medical care. OBJECTIVE: To compare the quality of medical care when generalists and cardiologists work separately or together in the management of patients with acute myocardial infarction (AMI). METHODS: We reviewed the charts of 1716 patients with AMI treated at 22 Minnesota hospitals between 1992 and 1993. Patients eligible for thrombolytic aspirin, beta-blockers, and lidocaine therapy were identified using criteria from the 1991 American College of Cardiology guidelines for the management of AMI. We compared the use of these drugs among eligible patients whose attending physician was a generalist with no cardiologist input, a generalist with a cardiologist consultation, and a cardiologist alone. RESULTS: Patients cared for by a cardiologist alone were younger, presented earlier to the hospital, were more likely to be male, had less severe comorbidity, and were more likely to have an ST elevation of 1 mm or more than generalists' patients. Controlling for these differences, there was no variation in the use of effective agents between patients cared for by a cardiologist attending physician and a generalist with a consultation by a cardiologist. However, there was a consistent trend toward increased use of aspirin, thrombolytics, and beta-blockers in these patients compared with those with a generalist attending physician only (P<.05 for beta-blockers only). Differences between groups in the use of lidocaine were not statistically significant. The adjusted probabilities of use of thrombolytics for consultative care and cardiologist attending physicians were 0.73 for both. Corresponding probabilities were 0.86 and 0.85 for aspirin and 0.59 and 0.57 for beta-blockers, respectively. CONCLUSIONS: For patients with AMI, consultation between generalists and specialists may improve the quality of care. Recent policy debates that have focused solely on access to specialists have ignored the important issue of coordination of care between generalist and specialist physicians. In hospitals where cardiology services are available, generalists may be caring for patients with AMI who are older and more frail. Future research and policy analyses should examine whether this pattern of selective referral is true for other medical conditions.