Emergency admissions of elderly patients constitute a major management issue due to the complexity of their problems. The aim of this retrospective observational study was to identify medical and social characteristics and crisis factors for emergency department (ED) hospitalization in elderly patients, and to evaluate the influence of these factors on the length of stay and outcome at discharge. During a 4-month period, 396 patients aged 70 years and older were referred to the ED of a University Hospital (Hĵpital Edouard Herriot) in Lyon, France. A questionnaire specifically designed for the study was completed for each patient using the information in the patients' files previously filled in by the "Rapid Geriatric Assessment Team" of the ED. We described civil and marital status, living conditions, reason for admission to ED and other associated pathologies according to the ICM-9, crisis factors, length of stay (LOS) and outcome at discharge. The mean age was 81.9 years (SD 6.5); two thirds (66.7%) of the study subjects were female, and 46.7% were widowed; the majority (68.7%) lived in their own homes. The main reasons for admission were cardiopulmonary diseases in 31.6% of cases, followed by neuropsychiatric disorders in 28.2%, and falls in 8.3%; a final category (31.8%) included subjects admitted for general, non-specific symptoms. Among the crisis factors observed, 49.4% presented an acute episode of a chronic illness, 33.6% lived alone, and 20.9% had been hospitalized during the 6-month period preceding the study. The average LOS was 3.15 days. The multivariate model showed that falls increase LOS by 74%, dementia by 65%, and depression by 21%. Upon discharge, 13% returned to their residence before hospitalization, 55% were transferred to a medical speciality ward, and 4% to other facilities, whereas only 19% were transferred to a geriatric ward, and 9% died during their stay in the ED. The multinomial model showed that outcome at discharge was influenced by functional dependency, dementia, depression, and acute episodes of a chronic illness. For many elderly, the ED remains a critical point of access to more complete managed care. This elderly population is comprised of polypathological, frail persons whose morbid state requires multidisciplinary management in geriatric units. The findings of this study suggest that interventions of multidisciplinary networks, such as home health care programs aimed at detecting crisis factors and establishing early prevention of crisis states, may improve unfavorable medical and social conditions and reduce hospitalization in geriatric patients.