Objective. Delirium is frequently observed, but generally under recognized in elderly hospitalized patients. The aims of this study were to determine the prevalence of delirium in elderly patients hospitalized at a university hospital, and to determine the recognition rate by hospital staff during hospitalization. Methods. The study included 108 consecutive patients aged >= 65 years that were hospitalized in the medical and surgical inpatient departments at Baskent University Hospital, Ankara, Turkey. All the patients were evaluated using the Mini Mental State Examination (MMSE) upon admission and Confusion Assessment Method (CAM) on a daily basis during hospitalization. Written documents and consultation requests from psychiatry and/or neurology departments were reviewed for recognition of delirium by hospital staff. Results. Among the 108 patients in the study, delirium was noted in 18 (16.7%) during their hospital stay. Consultation from psychiatry or neurology departments was requested for 5 of the 18 patients, only 1 with a delirium diagnosis, indicating that 17 of the cases (94.4%) were not recognized by their primary physicians. Conclusions. The delirium non-recognition rate in elderly hospitalized patients was very high. We think that hospital staff must be trained to recognize the symptoms of delirium and identify high-risk patients.