Background Revascularization surgery (RS) is the therapy of choice in moyamoya disease (MMD). Due to rarity of disease and ethical concerns, randomized controlled trials about the treatment options are lacking. Very little information is available on the long-term outcome of conservatively treated moyamoya patients. Aim We compared the long-term outcome of moyamoya patients treated conservatively to those who underwent RS. Methods Our study population included all patients with moyamoya disease/syndrome from 2002 to 2012. The demographic, clinical characteristic and imaging details were reviewed. The outcome was obtained prospectively. Results Of the 36 patients, 26 (72.2%) had MMD and 10 (27.8%) had moyamoya syndrome. The median age at onset of symptoms was 17.5 years (range, 10 months-55 years). Fifteen patients belonged to pediatric group and 21 were adults. All the pediatric patients had ischemic events at onset and 10 (47.6%) of the adults presented with hemorrhage. Twenty (55.6%) patients received conservative treatment and 16 (44.4%) underwent revascularization procedures. The median duration of follow-up was 28 months (range, 3-90 months). Three (18%) of the surgically treated patients had recurrent ischemic events on follow-up, but none of the conservatively treated patients had events. An excellent outcome (Modified Rankin Scale of ≤ 2) was seen in 12 (75%) surgically treated and 16 (94%) conservatively treated patients (p = 0.17). Conclusion Compared to East Asians, our patients had a lower stroke recurrence rate and good functional outcome even with conservative treatment. Future studies should focus on clinical and imaging predictors of progression to select moyamoya patients for RS. © 2013 Elsevier B.V. All rights reserved.