Objective: To assess the safety and efficacy of an Emergency Department Chest Pain Protocol in ruling out Acute Coronary Syndrome in a regional hospital in Singapore.Methodology: An audit was carried out of the cases admitted to our Short Stay Unit (SSU) under the Chest Pain Protocol from June to November 2014. Patients presenting with chest pain and possible acute coronary syndrome, but with normal initial electrocardiogram (ECG) and troponin level, could undergo this rule-out protocol, which comprised serial ECGs and troponin levels, followed by selective outpatient treadmill or Coronary Computed Tomographic Angiography (CCTA) if they were discharged.The list of patients was electronically generated from our database at fortnightly intervals. Their casenotes were then reviewed, and phone follow-up done for discharged patients at least 30 days after discharge.Primary outcome was missed Acute Coronary Syndrome (ACS) within 30 days, as determined by 2 independent cardiologists using pre-set criteria. Secondary outcomes were adverse events, and stable coronary artery disease (CAD) requiring Percutaneous Coronary Intervention (PCI).Results: During the period of audit, a total of 240 patients were admitted under the protocol, of which 3 were lost to follow-up. 4 patients were found to have ACS within 30 days, of which 3 were picked up by the protocol. There was 1 case of missed ACS, who had a negative treadmill after discharge from the SSU, but later had an ST-Elevation Myocardial Infarction (STEMI). 10 patients had stable CAD requiring PCI. Conclusion:Our results suggest that the protocol is safe and can rule out ACS in most patients.