Hospital length of stay (LOS) after acute myocardial infarction (AMI) has steadily decreased because of both improved treatments and cost considerations. Early discharge may adversely affect some patients who might benefit from extended monitoring. The Minnesota Heart Survey was a population-based study of patients with AMI in acute-care hospitals in the Minneapolis-St. Paul, Minnesota, metropolitan area. Medical records were abstracted for a random sample of patients hospitalized with AMI in 1985, 1990, 1995, and 2001. Case fatality rates, adjusted for age and gender, were identified using mortality data from the index hospitalization and Minnesota death certificates. A total of 4,940 patients with a validated AMI were identified from the combined 1985 (n = 1,306), 1990 (n = 1,550), 1995 (n = 1,087), and 2001 (n = 515) surveys. Median LOSs were 9, 8, 6, and 4 days, respectively. Patients hospitalized <or=4 days formed an increasing proportion of the population, from 11% (1985) to 58% (2001). In-hospital case fatality rates decreased from 1985 to 2001 (11.6% to 5.4%; p <0.0001 for trend). There was a significant decrease in both 1- (3.3% to 2.4%; p = 0.002 for trend) and 6-month (8.9% to 5.4%, p <0.0001) mortality rates after discharge from 1985 to 2001. In conclusion, the progressive and substantial decrease in hospital LOS after AMI in the past 2 decades was not associated with increased mortality after discharge. These decreases in LOS were associated with increasing use of effective therapies.