Diagnosing ischaemic stroke and determining its cause is difficult in children. Both are important for selection of treatment and prediction of outcome. This study explored the diagnostic changes that lead to a delay in the correct diagnosis of paediatric stroke. Case histories of 45 children with ischaemic stroke (31 males, 14 females; median age 6y; age range 2mo-16y) were retrospectively reviewed. The initial clinical diagnosis, based on the interpretation of presenting symptoms, was compared with the final aetiological stroke diagnosis after completion and review of diagnostic work-up. The type of diagnostic change, consequent time delay until correct diagnosis, reasons for change of diagnosis, and alterations to management were evaluated. Twenty-four diagnostic changes were identified; 19 in 'primary stroke diagnosis' (symptoms initially not attributed to stroke), and five in 'aetiological diagnosis' (incorrect initial determination of type or cause of stroke). The median interval between initial and final diagnosis was 7 days (3h-2y). The change in diagnosis led to therapeutic alterations in 17 patients. Risk factors for childhood stroke differ from those in adults. Stroke is frequently not recognized as the cause of the child's symptoms, and the correct determination of stroke aetiology takes time. We recommend that children with stroke be evaluated in a centre with expertize, using standardized diagnostic protocols and careful follow-up.