Objective:To improve the Rapid Arterial Occlusion Evaluation (RACE) scale and to investigate its value in identifying large vessel occlusion (LVO) in patients with acute anterior circulation ischemic stroke (AIS).Methods:Consecutive patients with AIS treated in Liangxiang Hospital of Fangshan District, Beijing through stroke easy access from January 1, 2016 to December 31, 2018 were enrolled prospectively. The clinical data and multimodal CT examinations required to determine LVO were collected. The existing problems in the RACE score were modified. The patients were evaluated by the modified RACE score, RACE score, and National Institute of Health Stroke Scale (NIHSS). The receiver operator characteristic (ROC) curve was used to evaluate the predictive ability of the modified RACE score for LVO, and it was compared with the RACE score and NIHSS score. The ROC curves of LVO predicted by modified RACE score and NIHSS score in patients with left and right hemispheric lesions were compared.Results:A total of 184 patients were included, of which 66 (35.9%) had LVO. The age (64.8±11.7 vs. 60.5±10.8 years; t=2.483, P=0.014), baseline NIHSS score (13 [6.75-17] vs. 5 [2-9]; Z=-6.361, P<0.001) and the proportion of patients with gaze (37.9% vs. 17.4%; χ2=4.696, P=0.030) in the LVO group were significantly higher than those in the non-LVO group. ROC curve showed that the modified RACE score was more effective in identifying LVO than RACE score (area under the curve: 0.812 vs. 0.770; Z=4.654, P<0.001). The best cutoff value of the modified RACE score in predicting LVO was 5, and its predictive sensitivity and specificity were 75.8% and 75.4%, respectively, and the positive and negative predictive values were 63.3% and 84.8%, respectively. A comparison of patients with left hemispheric lesion and those with right hemispheric lesion showed that the ability of the modified RACE score in predicting LVO was more balanced (area under the curve: 0.826 vs. 0.796; Z=0.454, P=0.650), while there was a significant difference in NIHSS score (area under the curve: 0.856 vs. 0.703; Z=2.149, P=0.031). Conclusions:The modified RACE score is better than the original RACE score in the predictive value of LVO in patients with AIS, and its predictive power of LVO in patients with left and right hemisphere stroke is more balanced than the NIHSS score, which may help clinical discrimination and screening for patients suitable endovascular treatment.