Acute coronary syndromes (ACS) are the most common cardiovascular diseases and are associated with a significant risk of mortality and morbidity. The Global Registry of Acute Coronary Events (GRACE) risk score postdischarge is a widely used ACS prediction model for risk of mortality (low, intermediate, and high); however, it has not yet been validated in patients from the Arabian Gulf. This prospective multicenter study (second Gulf Registry of Acute Coronary Events) provides detailed information of the GRACE risk score postdischarge in patients from the Arabian Gulf. Its prognostic utility was validated at 1-year follow-up in over 5000 patients with ACS from 65 hospitals in 6 Arabian Gulf countries (Bahrain, Saudi Arabia, Qatar, Oman, United Arab Emirates, and Yemen). Overall, the goodness of fit (Hosmer and Lemeshow statistic P value =.826), calibration, and discrimination (area under the receiver operating characteristic curve = 0.695; 95% confidence interval: 0.668-0.722) were good. The GRACE risk score postdischarge can be used to stratify 1 year mortality risk in the Arabian Gulf population; it does not require further calibration and has a good discriminatory ability.