The aim of this study was to propose a classification system for childhood arterial ischaemic stroke (AIS). Subtypes from the Trial of Org 10172 in Acute Stroke Therapy (TOAST) classification, previously shown to be applicable to children, were retained in the proposed Paediatric Stroke Classification (PSC). Additional important paediatric AIS aetiologies were identified from a literature review. Preliminary validation was performed by three raters who categorized clinical vignettes from 135 patients (66 male; median age 6.3y, range 0.1 to 16y). Eight aetiological subtypes were identified and defined, as follows: (1) sickle cell disease; (2) cardioembolic; (3) moyamoya syndrome; (4) cervical arterial dissection; (5) steno-occlusive cerebral arteriopathy; (6) other determined aetiology; (7) multiple probable/possible aetiologies; and (8) undetermined aetiology. There was very good agreement between the raters about categorization of the vignettes. Causes of disagreement were identified and final categories and definitions were modified accordingly. We conclude that the PSC enables the categorization of children with AIS into aetiological subtypes relevant to this age group. This will be useful in multicentre studies of natural history and treatment but will require further independent validation.