Postoperative delirium is associated with impaired cognitive outcome, longer hospital stay and an increased risk of dementia. To date, the pathophysiology of delirium remains largely unknown. Therefore, we studied the association of preoperative brain MRI features and the occurrence of postoperative delirium in a large group of older patients. We measured preoperative brain volumes, white matter hyperintensity shape, cerebral infarcts and cerebral perfusion. Preoperative cortical brain infarct volume was associated with postoperative delirium. Other preoperative brain MRI features were not significantly associated with postoperative delirium. Patients with a larger burden of cortical infarcts may have a decreased brain reserve, increasing the risk of postoperative delirium.