This study compares the symptom profile of patients with postoperative delirium after femoral neck fracture surgery in those with and without dementia. In this study, 129 patients of age >= 70 years (mean age +/- SD, 86 +/- 6 yr, 72% women) with postoperative delirium, were included. Delirium and dementia were diagnosed according to the Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition) criteria. Of the 129 patients with delirium, 54 (42%) had a dementia disorder. Patients with delirium superimposed on dementia more often had any hyperactive and pure emotional delirium. Communication difficulties and symptoms such as restlessness/agitation, aggressive behavior, and irritability were more commonly found in the dementia group. In contrast, patients with delirium but without dementia were more often diagnosed with pure hypoactive and any psychotic delirium. The symptom profile of postoperative delirium varies according to whether it occurs in patients with or without dementia. This may indicate that postoperative delirium among patients with hip fracture differs based on the presence or absence of dementia.