SIGNIFICANCE OF THE STUDY: Acute myocardial infarction (AMI) is a major cause of death in Korea. Delay in seeking treatment may cause unnecessary exacerbation of the disease and early mortality from AMI. Patients' recognition of symptoms of an AMI and response to those symptoms may influence the delay time. Bystanders' role in patients' seeking treatment after AMI has not been studied in previous research. Understanding reasons for delay in seeking treatment is important in developing interventions for reducing these delays and increasing survival rate from AMI. PURPOSE OF THE STUDY: A retrospective survey was conducted with 144 AMI patients to: (1) investigate time from symptom onset to arrival at the first hospital for treatment of AMI; (2) describe patient's and bystander's response to the patient's symptoms; (3)examine whether patient's and bystander's responses affect delay time. RESULTS: The mean of overall pre-hospital delay time was 13.64 (21.86) hours and it consisted of patients' delay of 13.64 (22.32) hours and transportation time of 24.86 (19.41) minutes. People living in rural area delayed longer than people living in urban area. Pre-hospital delay time was associated with the bystander: patients delayed longer when they were with their spouse, family and friends than when with colleagues at work. Calling 119 saved transportation time, but did not reduce overall pre-hospital delay time. CONCLUSION AND SUGGESTIONS: Patients delay longer than the time window for a successful reperfusion therapy when they experience symptoms of AMI; and calling 119 does not diminish this delay. Bystanders' adequate response to the patients' symptom may reduce the delay time in seeking treatment. Findings from this study may suggest that health education and public campaigns are needed to increase people's recognition of symptoms of an AMI and to promote adequate response from bystanders to the AMI symptoms. In addition, public campaigns urging car operators to yield to the emergency vehicle are needed in order to reduce transportation time.