OBJECTIVE: Revascularization is an effective treatment for the ischemic symptom of moyamoya disease. Indirect revascularization is also effective. Magnetic resonance angiography (MRA) has the ability for collateral formation that is equivalent to conventional angiography. This study analyzed the results of indirect revascularization by MRA. METHODS: A total of 25 patients underwent bilateral EDAS for the management of moyamoya disease. All patients underwent MRA after surgery more than 24 months later. The collateral formation was graded as Good, Fair, and Poor. The clinical outcome was assessed as Excellent, Good, Fair, and Poor. RESULTS: Good collateral formation was 32 sides of the EDAS, and fair was 18. An excellent clinical outcome was obtained in 15 patients, Good in 8, Fair in 1, and Poor in 1. There was a significant correlation between the preoperative symptom, gender, and the clinical outcome. CONCLUSION: In the management of ischemic moyamoya disease, indirect revascularization has been the golden standard with remarkably low morbidity and mortality. Moreover, and MRA can replace conventional angiography in the follow-up of moyamoya patients.