Detection of cognitive impairment among hospitalized older individuals has shown to be insufficient. A point prevalence study in two geriatric hospitals in Helsinki, Finland, was performed among 219 acutely ill individuals over 70 years to assess the detection of dementia and delirium. Documentation of dementia and delirium in medical records, and recordings of confusional symptoms in nurses' notes were compared with the researchers' diagnosis made after a detailed assessment of cognitive status. The cognitive decline was mentioned in medical records in 70/88 (79.5%) of the cases. Cognitive testing was performed on 42/88 (47.7%) of the dementia patients, and the diagnosis of dementia was recorded in 47/88 (53.4%) of them. A specific etiological diagnosis was recorded in only 4/88 (4.5%) cases. Cognitive impairment in at least one of these four means was recorded in 80/88 (90.9%) of cases (sensitivity 0.93). Eight patients had a false-positive diagnosis of dementia (specificity 0.94). Delirium was diagnosed in 77 (35.2%) patients by the researchers, but it was recorded in only 31/77 (40.3%) in medical records. In 64/77 (83.1%) cases signs of confusion were recorded in nurses' notes. Poor detection and documentation may lead to undertreatment of both disorders.