Objective：To investigate the relationship between serum level of repulsive guidance molecule a（RGMa） and leptomeningeal collateral status（LMCs） in patients with acute cerebral infarction. Methods：This study included in 96 patients with acute ischemic stroke with middle cerebral artery occlusion，and meanwhile 33 healthy controls. According to regional leptomeningeal collateral（rLMC） score，they were classified as poor LMCs group and good LMCs group. The serum RGMa levels were detected by enzyme-linked immunosorbent assay（ELISA） test. Multivariate logistic regression analysis was used to examine the independent predictors of poor LMCs in the patients. The receiver operating characteristic curve（ROC curve） was obtained to explore RGMa levels in predicting poor LMCs. Results：Serum RGMa levels in poor LMCs group[5 588.8（4 247.9，10 311.5） pg/mL] were significantly higher than those in good LMCs group[3 103.9（2 096.5，3 970.2） pg/mL] as well as healthy controls[3 528.6（2 801.2，5 328.5） pg/mL] （all P<0.05）. Based on the ROC curves，the best cut-off point of serum RGMa for predicting poor LMCs was 4 197.745 pg/mL，and the sensitivity and specificity were 76.5% and 80.0%，respectively. The logistic regression analysis showed that RGMa≥4 197.745 pg/mL remained an independent predictor of poor LMCs（OR=0.119，95%CI=0.030-0.469，P=0.002）. Conclusion：Serum RGMa is an independent predictor of poor LMCs in patients with acute cerebral infarction.