OBJECTIVE: To assess outcome of residual brain arteriovenous malformation (BAVM) after stereotactic radiosurgery. METHODS: Patients with residual BAVM 3 years after radiosurgery were retrospectively included. Demographics, angioarchitectural characteristics, complications, bleeding, and cure rates of patients with intervention or conservative management (i.e., observation) were compared. We analyzed characteristics of patients treated conservatively who achieved cure or still had persistent BAVMs during follow-up. RESULTS: The study included 87 patients including 5 patients with subtotal obliteration with a mean follow-up time of 33.7 +/- 36.6 months. Of patients, 27 (31.0%) received subsequent treatment (radiosurgery, n = 23; microsurgery, n = 3; embolization, n = 1), and 60 (69%) were treated conservatively. After repeat SRS, 4 (14.8%) patients experienced symptomatic complications after the second treatment, and 7 (25.9%) experienced asymptomatic changes. Three (3.4%) patients, all of whom presented initially with a ruptured BAVM, experienced hemorrhage during follow-up. Subsequent treatment was effective with a complete cure of BAVM in 11 patients (40.7%). Complete resolution of the residual BAVM occurred in 15 (25%) patients treated conservatively. CONCLUSIONS: Complete obliteration of a significant number of residual BAVMs may occur 3-5 years after the first irradiation, whereas increased radiation dose associated with repeat SRS may lead to an increased risk of complications. The fact that the interval risk of bleeding decreased after SRS (especially for ruptured BAVM) lends further strength to the argument for a conservative management approach for residual BAVM 3-5 years after the first irradiation.