A 53-year-old male presented with a subarachnoid haemorrhage secondary to an anterior communicating artery aneurysm rupture. The aneurysm was successfully treated with intravascular coiling. Post-haemorrhage the patient showed a profound amnestic syndrome with deficits in anterograde (and also retrograde) memory, confabulation and personality changes consistent with the anterior communicating artery syndrome (ACAS). Magnetic resonance imaging showed basal forebrain and orbitofrontal infarction. The patient was treated with donepezil (a cholinesterase inhibitor) without symptomatic improvement or clinically meaningful change in his psychometric testing. The clinical and neuropsychological features and the pathological basis of the ACAS are reviewed.