Aim:Ischaemic moyamoya disease (MMD) can affect both children and adults; however, there seem to be differences in brain perfusion stages defined by the computerised tomography perfusion (CTP) image scale system before surgery. In this study, we aimed to clarify perfusion differences and determine whether children and adults respond similarly to surgical prevention and how brain perfusion stages before surgery predict outcomes in ischaemic MMD in children and adults.Material and Methods:A total of 355 patients with ischaemic MMD, including 74 children and 281 adults, were enrolled in the study. CTP scans were used to identify the perfusion status according to a novel staging system of the pre-infarction period. The perfusion status of each hemisphere between the children and adult groups was analysed. The modified Rankin scale was used during long-term follow-up as an indicator of clinical outcomes.Results:The proportions of stages 0 and Ⅳ in adults were significantly higher than those in children (p = 0.09 and p = 0.003, respectively). Stage Ⅲ was more common in the children’s group (p = 0.001). The stroke data showed an increasing tendency in the infarction rate from stages I to Ⅳ. Both groups in stage 0 and in the early stages had a similar highly improved ratio after surgery; the children, however, achieved significantly better clinical outcomes in stage Ⅲ and late stages.Conclusion:There are differences in the perfusion status between child and adult patients with MMD. The pre-infarction staging system is associated with MMD-related stroke to some extent. Children have a greater chance for improvement than adults in stage Ⅲ and later stages.