Background: The etiologic factors of delirium have been frequently studied in hospitalized elderly patients who usually have an underlying disorder, i.e., hip fracture or dementia predisposing to delirium. The etiologic factors of delirium and prognosis in healthy elderly remain unstudied. The aim of our study was to detect the primary and additional etiologic factors contributing to delirium among community-dwelling healthy elderly people without predisposing disorders to delirium and to evaluate 1-year prognosis after discharge to home. Method: The study subjects consisted of 51 community-dwelling people over 65 years of age, without severe underlying disorders predisposing to delirium, admitted consecutively to the hospital because of a delirious state. The diagnosis of delirium was based on the DSM-III-R criteria. After discharge to home, the subjects were followed up for 1 year. Results: The most important primary causes of delirium were infections in 22 cases (43%) and cerebrovascular attacks in 13 cases (25%). After the 1-year follow-up period, 10 patients (20%) had been taken into long-term care and 5 patients (10%) had died. Discussion: The plausible etiologic factor of delirium was detected in all cases. Among healthy elderly people, infections and cerebrovascular attacks were the most important etiologic factors for delirium. After discharge to home, 30% of the patients had to be taken into long-term care or had died within 1 year of the delirium.