Chest pain is one of the most common complaints at the emergency department (ED), and it is commonly the perceived likelihood of acute coronary syndrome (ACS) that drives management. Guidelines from the European Society of Cardiology (ESC) recommend the use of a 0-/1-h high-sensitivity cardiac troponin T (hs-cTnT) protocol to rule out or in ACS, but this is mostly based on observational studies. The aim of the ESC-TROP trial is to determine the safety and effectiveness of the ESC 0-/1-h hs-cTnT protocol when implemented in routine care. Adult chest pain patients at 5 EDs in the Skåne Region, Sweden, are included in the trial. The 0-/1-h hs-cTnT ESC protocol supplemented with clinical assess-ment and electrocardiography (ECG) is implemented at 3 EDs, and the other 2 EDs act as concurrent controls. Out-comes will be evaluated during the 10 months after the implementation and the corresponding 10 months of the previous year. The 2 co-primary outcomes are (a) acute myocar-dial infarction (AMI) and all-cause death within 30 days in patients discharged from the ED, and (b) ED length of stay of the same patients. Secondary outcomes include the proportion of chest pain patients discharged from the ED and the number of ruled-out patients undergoing objective testing within 30 days. The ESC-TROP trial will determine the performance and applicability of the 0-/1-h hs-cTnT ESC protocol supplemented with clinical assessment and ECG when implemented in routine ED care. It will provide evidence wheth-er 0-/1-h hs-cTnT testing is safe, effective, and feasible, and whether widespread implementation as recommended by ESC guidelines should be supported.