BACKGROUND: Early diagnosis and treatment of myocardial infarction can prevent life-threatening complications such as dysrhythmias and death. The aim of this study was to determine the length of delay and its related factors in seeking treatment among a group of patients with myocardial infarction. METHODS: In a cross-sectional design, all the patients who had referred to a general teaching hospital (Kashan, Iran) for treatment of myocardial infarction from April 2004 to March 2005 were recruited. Demographic characteristics, the amount of delay, and the causes of having delay were recorded. RESULTS: Two hundred patients were recruited for this study from which 131 (69%) patients had delay in seeking treatment. Factors such as gender, age, economical status, educational level, referring to a general physician before referring to the hospital, the severity of symptoms, residential place (urban vs. rural), and the time of the onset of the symptoms (day vs. night) were determined to be related to having delay. The most important causes of having delay were: "hoping the symptoms to alleviate spontaneously", "attributing the symptoms to other problems other than heart problems", and "disregarding the symptoms". CONCLUSION: Regarding the most important causes of having delay in this study, the importance of educating people about the symptoms of myocardial infarction and the importance of early referral to the hospitals is clarified. Keywords: Prehospital delay, Myocardial infarction, Onset-to-door time.