Aim Delirium is responsible for up to 56% of hospital admissions in the elderly. Epilepsy and delirium share most risk factors and are both associated with confusion. The aim of this work was to study whether a link between epileptic activity (EA) and delirium existed, and if this link was relevant. Methods Charts of patients aged over 65 years admitted for delirium at the emergency room in 2011 were retrospectively reviewed. Risk factors for delirium, past medical history, medications, biological and iconographic work‐up were analyzed. Those characteristics were compared in patients who had electroencephalogram (EEG) with those who had not. Clinical characteristics of patients with EA on EEG were compared with the patients without EA. Results A total of 177 charts were analyzed. The only parameters associated with the realization of an EEG were anti‐epileptic drug treatment and subdural hematoma. A total of 56% (98/177) of patients had EEG. A total of 84% of EEG were abnormal. EA were present in 15% of EEG: 12 with interictal epileptiform discharges and three with non‐convulsive status (NCSE). In multivariate analysis, only dehydration and the use of anticholinergic drugs were associated with EA. Outcome showed a trend for longer hospital stay and a higher institutionalization rate for patients with delirium who had EA. Conclusion EA occur in a significant proportion of delirium, and possibly have a role in the prognosis and pathophysiology of this disorder. Almost no anomalies can distinguish a priori patients in delirium who will have EA. EEG should be carried out in all older patients with delirium. Geriatr Gerontol Int 2013; 14: 447–451.