Seventy consecutive elderly patients meeting the DSM-III criteria for non-alcohol delirium were examined during the acute stage and followed to four years later. The mean age of the patients at the beginning of the index admission was 74, 8±6, 4 years. The most common aetiologies for delirium were stroke, infections and metabolic disorders. Coexistent structural brain disease predisposing to delirium was found in 57 cases (81%). During the index admission, the cognitive dysfunction associated with delirium ameliorated significantly (mean±S.D. Mini Mental State Examination score 9·7±6·6 at admission and 13·9±7·2 at discharge, P < 0·001), but during the follow-up period of four years progression of the basic central nervous system disease was observed together with declining cognition and deteriorating functions of daily living. Four patients died during the index admission and 42 patients during the follow-up period. In deceased patients there was a statistically significant connection between the levels of cognitive functioning and functions of daily living at the end of the index admission and the life span after delirium.