Reversible cerebral vasoconstriction syndrome (RCVS) is a clinicoradiological diagnosis comprising ‘thunderclap’ headaches and reversible segmental vasoconstriction of cerebral arteries, occasionally complicated by ischaemic or haemorrhagic stroke. We report a case of RCVS in a 13-year-old male with severe thunderclap headaches and no focal neurological signs. Brain imaging showed multiple posterior circulation infarcts; cerebral computed tomography, magnetic resonance imaging, and catheter angiography showed multifocal irregularity and narrowing, but in different arterial segments. Laboratory studies did not support a diagnosis of vasculitis. Symptoms resolved over 3 weeks; magnetic resonance angiography 3 months later was normal and remained so after 2 years. We highlight the typical clinical features of RCVS in this case and suggest that the diagnosis should be considered in children with thunderclap headaches or stroke syndromes where headache is a prominent feature, especially if cerebrovascular imaging studies appear to be evolving or discrepant.