Clinical assessment is pivotal in diagnosing acute coronary syndrome. Our study aimed to identify clinical characteristics predictive of major adverse cardiac events (MACE) in an Asian population and to derive a risk score for MACE. Patients presenting to the emergency department (ED) with chest pain and non-diagnostic 12-lead electrocardiograms were recruited. Clinical history was recorded in a predesigned template. Random glucose and direct low-density lipoprotein measurements were taken, in addition to serial troponin. We derived the age, coronary risk factors (CRF), sex and symptoms (ACSS) risk score based on multivariate analysis results, considering age, CRF, sex and symptoms and classifying patients into very low, low, moderate and high risk for MACE. Comparison was made with the ED Assessment of Chest Pain Score (EDACS) and the history, electrocardiogram, age, risk factors, troponin (HEART) score. We also modified the HEART score with the CRF that we had identified. The outcomes were 30-day and 1-year MACE. There were a total of 1689 patients, with 172 (10.2%) and 200 (11.8%) having 30-day and 1-year MACE, respectively. Symptoms predictive of MACE included central chest pain, radiation to the jaw/neck, associated diaphoresis, and symptoms aggravated by exertion and relieved by glyceryl trinitrate. The ACSS score had an area under the curve of 0.769 (95% confidence interval [CI]: 0.735-0.803) and 0.760 (95% CI: 0.727-0.793) for 30-day and 1-year MACE, respectively, outperforming EDACS. Those in the very-low-risk and low-risk groups had <1% risk of 30-day MACE. The ACSS risk score shows potential for use in the local ED or primary care setting, potentially reducing unnecessary cardiac investigations and admission.