The purpose of this study was to identify factors associated with in-hospital delay in patients with acute myocardial infarction (AMI) in Japan. In this observational study, 155 consecutive patients admitted with AMI to one of five urban hospitals were studied. The median door-to-needle time and door-to-catheterization-laboratory time was 19 min and 60 min, respectively. Three variables predicted door-to-catheterization-laboratory times >/= 60 min: failing to call an ambulance, direct admission to the hospital, and absence of diaphoresis (p < 0.05). These findings support the need for public education emphasizing the importance of calling an ambulance for AMI symptoms. Moreover, Japanese physicians should be aware that admitting patients directly to the hospital and bypassing the Emergency Department might increase delay to treatment.