Despite the availability of safe and effective drugs for the treatment of acute myocardial infarction, nowadays, only a minority of patients arrive at the hospital early enough to receive the benefit of these treatments. The reason for this is still uncertain. Our intention was to review the literature on this topic, check if there were some issues that could be identified as delay-promoters, and see if any Italian data were available, in order to make a comparison with international data. We found a substantial agreement among the Authors that median total delay (i.e. the time between the onset of symptoms and the arrival at the hospital) is between three and five hours, and it seems that this has remained fairly stable over the years. The decision delay (i.e. the time between the onset of symptoms and the first medical contact) is almost unanimously indicated as the major single component in the total delay. This represents around 40% of the pre-hospital phase. Transportation time appears to play only a slight role, if indeed any, in the total delay. Nonetheless, mobile coronary units have consistently shown that they can reduce thrombolysis time (e.g. the time between the onset of symptoms and the start of thrombolytic infusion) by almost 60 minutes, and this time-gain is comparable with the reduction in total delay obtained in Sweden with a media campaign. Strongly contrasting results were obtained from the analysis of the delay-determining factors.(ABSTRACT TRUNCATED AT 250 WORDS)