We describe the case of a 46-year-old female who presented with recurrent episodes of cerebrovascular events. She had an unremarkable family history and no risk factors for stroke, apart from smoking. A transthoracic echocardiogram with 'bubble' contrast was normal. However transoesophageal echocardiography demonstrated an aneurysm of the membranous part of the ventricular septum, representing the likely source of thrombo-embolisation. This case highlights the need for a systematic and rigorous approach to the investigation of young patients with stroke.