Our objective was to validate the Global Registry of Acute Coronary Events (GRACE) risk score for in-hospital mortality in a Middle Eastern acute coronary syndrome (ACS) population enrolled in the Gulf Registry of Acute Coronary Events (Gulf RACE). Out of 8176, unselected, consecutive patients with ACS, during 6 months in 2006 and 2007 from 63 hospitals in 6 Arab countries in the Middle East Gulf region, 7709 (94.3%) with available data were included. The main outcome measures were discriminatory performance (using C-index) and calibration of the GRACE risk score (in-hospital mortality predicted by GRACE risk score versus the actual mortality). In-hospital mortality in the Gulf RACE was 3.09% (n = 238). The discriminatory performance of the GRACE risk scores in the Gulf RACE was good overall (C-index = 0.86). Observed and predicted risk corresponded well in each stratum of risk of in-hospital mortality. This suggests its suitability for clinical use in this patient population.