Patients presenting at the emergency department with acute chest pain and suspected to represent an acute coronary syndrome were classically admitted as routine to the cardiology department, resulting in expensive and time-consuming evaluations. However, 2-5% of patients with acute coronary syndromes were discharged home inappropriately, resulting in increased mortality. To address the inability to exclude the diagnosis of acute coronary syndrome, chest pain units were developed, particularly in the United States. These provide an environment where serial electrocardiograms, cardiac biomarkers, and provocative testing can be performed to confirm or rule out an acute coronary syndrome. Eligible candidates include the majority of patients with non-diagnostic electrocardiograms. The results have been impressive; chest pain units have markedly reduced adverse events, while simultaneously increasing the rate of safe discharge by 36%. Despite evidence to suggest that care in chest pain units is more effective for such patients, the percentage of emergency or cardiology departments setting up chest pain units remains low in Europe.