OBJECTIVE:  To examine changes in the rate of beta‐blocker (BB) use at admission, in hospital, and at discharge between 1994 and 1995 (MICH I) and 1997 (MICH II) in patients with acute myocardial infarction (AMI). DESIGN:  Comparison of two prospectively enrolled cohorts. SETTING:  Five mid‐Michigan community hospitals. PATIENTS:  We studied 287 MICH I patients and 121 MICH II patients with AMI who had no contraindications to BB use from cohorts of consecutively admitted cases of AMI (814 in MICH I; 500 in MICH II). RESULTS:  Prescription of BBs to ideal patients with AMI increased in patients with previous history of myocardial infarction on arrival at the hospital (12.5% vs 36.0%; P= .01), in hospital (47.0% vs 76%; P < .01), and at discharge (34.0% vs 61.9%; P < .01). Neither race nor gender was a predictor of BB use. Younger age predicted BB prescription at discharge (odds ratio OR, 2.07; 95% confidence interval CI, 1.32 to 3.23). Later study cohort was the most important predictor of BB use in hospital (OR, 3.4; 95% CI, 2.09 to 5.25). CONCLUSION:  BB use improved dramatically over the study period, but additional work is needed to improve use of BB after discharge and among elderly patients with AMI.