Up till now ST-segment elevation myocardial infarction (STEMI) is an important clinical and epidemiological question because of its high incidence and death rate. In this light, intervention principles continue to be developed to reach a precise diagnosis and a fast transport of the patient towards adequate hospitals. As the only instrument able to modify the natural course of this disease is the early restoration of coronary flow in the myocardial ischemic area, we can understand that time to reperfusion is the driving parameter in defining sanitary and therapeutic ways aimed at facing up to this pathology in its acute phase and limiting the subsequent chronic disfunction. Recently, our group have published a paper demonstrating the fundamental importance of reperfusing the patient within 90 minutes from the onset of the AMI symptoms.The aim of this article is to give a state of art of the international literature about timing question in STEMI and to underline that from our results emerges the necessity of a critical revision of the actual guidelines in order to allow a real optimization and therapy of this pathology.