Churg-Strauss syndrome (CSS) is a systemic small-vessel vasculitis characterised by the presence of asthma and eosinophilia. Central nervous system involvement (cerebral infarctions or intracerebral haemorrhage) is rare in CSS. Spontaneous subarachnoid hemorrhage (SAH) has been described in other systemic vasculitides. SAH is exceptional in CSS. We present a 47-year-old woman with CSS presenting as a spontaneous SAH with cerebral angiography findings consistent with vasculitis of the basilar artery and without aneurysms or arteriovenous malformations. She received treatment with prednisone and cyclophosphamide, and 2 months later the basilar artery was normal on magnetic resonance angiography.