We report our experience with competence development in the performance of high flow extracranial-to-intracranial (HF EC-IC) bypass surgery because of the infrequency of, and hence potential exposure to, this challenging surgery. We reviewed the National Hospital Morbidity Database for the incidence of EC-IC bypass surgery as well as a prospectively collected database (institutional experience). The following were recorded from the institutional experience: graft occlusion, stenosis, disruption, distal ischaemia, surgical complications of the bypass leading to a modified Rankin Scale (mRS) score >2, and intraoperative cross-clamping time. The cross-clamping time was considered the total time that circulation may have been impaired, which included both the distal and proximal cross-clamping periods. The Australian national EC-IC bypass rate (of all bypass types) averaged 1.9 cases per 1,000,000 head of population annually. The institutional experience (170 cases) of high flow EC-IC bypass in this series was associated with 14.7% (95% confidence interval [CI] 10.1-20.9) of graft complications. Graft-specific complications leading to a mRS score >2 were 5.9% (95% CI 3.1-10.6). For the 83 patients where the cross-clamping time was known, the time of cross-clamping was 44 ± 14 min. We concluded that HF EC-IC bypasses are rarely performed procedures that challenge the development of surgical competence. Novel ways of developing and maintaining surgical skills are necessary, including simulation and laboratory experience.