The aim of the Chest Pain Unit at Policlinico Umberto I in Rome was to implement simple diagnostic flow-charts in subjects with non-traumatic chest pain for an early identification of patients at high, intermediate and low risk of acute coronary syndrome (ACS). A total of 4.74% of all patients admitted to the Emergency Department were hospitalized in the Chest Pain Unit. 15.72% of them received a diagnosis of atypical chest pain with low risk of ACS; 26,42% were diagnosed of stable angina pectoris; 11.37% were affected by chronic coronary heart disease with medium risk of ACS and 12.83% were at high risk of acute coronary syndrome.