Delay in seeking medical care after symptom onset in patients with an acute myocardial infarction (AMI) is related to increased morbidity and mortality. Duration of prehospital delay in patients hospitalized with AMI has not been well characterized over time, and potentially changing patient characteristics associated with prolonged delay are not well understood. The study sample consisted of 5,967 residents (mean age 76 years; 39% women) of the Worcester, Massachusetts, metropolitan area hospitalized with AMI in 11 annual periods from 1986 to 2005. Mean and median delay times have remained essentially unchanged during the past 2 decades. Mean and median prehospital delay times were 4.1 and 2.0 hours in 1986, 4.7 and 2.2 hours in 1995, and 4.6 and 2.0 hours in 2005, respectively. Approximately 45% of patients with AMI presented within 2 hours of acute symptom onset, whereas an additional one third presented from 2 to 6 hours after the onset of acute coronary symptoms. Advancing age and history of either diabetes or MI were associated with prolonged delay. Compared with patients arriving within 2 hours of symptom onset, those with prolonged prehospital delay were less likely to receive thrombolytic therapy and percutaneous coronary intervention within 90 minutes of hospital arrival. In conclusion, results of this population-based study suggest that a large proportion of patients with AMI continue to show prolonged prehospital delay.