We sought to determine how often angiotensin-converting enzyme (ACE) inhibitors are prescribed as a discharge medication among eligible patients > or = 65 years old with an acute myocardial infarction; to identify patient characteristics associated with the decision to prescribe ACE inhibitors; and to determine the factors associated with the decision to obtain an evaluation of left ventricular function among patients who have no contraindications to ACE inhibitors. We addressed these aims with an observational study of consecutive elderly Medicare beneficiary survivors of an acute myocardial infarction hospitalized in Alabama, Connecticut, Iowa, and Wisconsin between June 1992 and February 1993. Among the 5,453 patients without a contraindication to ACE inhibitors at discharge, 3,528 (65%) had an evaluation of left ventricular function. Of the 1,228 patients without a contraindication to ACE inhibitors who had a left ventricular ejection fraction < or = 40%, 548 (45%) were prescribed the medication at discharge. In a multivariable analysis, an increased prescribed use of ACE inhibitors at discharge was correlated with several factors, including diabetes mellitus, congestive heart failure, ventricular tachycardia, and loop diuretics as a discharge medication. Patients admitted after the publication of the Survival and Ventricular Enlargement (SAVE) trial were significantly more likely to receive ACE inhibitors, although the absolute improvement in utilization was small in the 6 months after the trial results were published. In conclusion, improving the identification of appropriate patients for ACE inhibitors and increasing the prescription of ACE inhibitors for ideal patients may provide an excellent opportunity to improve care.