We studied the factors influencing the choice of admission to Geriatrics units, instead of other acute hospital units after an emergency visit. We report the results from a cohort of 1283 randomly selected patients aged >75 years hospitalized in emergency and representative of the French University hospital system. All patients underwent geriatric assessment. Baseline characteristics of patients admitted to Geriatrics and other units were compared. A center effect influencing the use of Geriatrics units during emergencies was also investigated. Admission to a Geriatrics unit during the acute care episode occurred in 499 cases (40.3%). By multivariate analysis, 4 factors were related to admission to a Geriatrics unit: cognitive disorder: odds ratio (OR)=1.79 (1.38-2.32) (95% confidence interval=95% CI); "failure to thrive" syndrome OR=1.54 (1.01-2.35), depression: OR=1.42 (1.12-1.83) or loss of Activities of Daily Living (ADL): OR=1.35 (1.04-1.75). The emergency volume of the hospital was inversely related to the use of Geriatrics units, with high variation that could be explained by other unstudied factors. In the French University Emergency Healthcare system, the "geriatrics patient" is defined by the existence of cognitive disorder, psychological symptoms or installed loss of autonomy. Nevertheless, considerable nation-wide variation was observed underlining the need to clarify and reinforce this discipline in the emergency healthcare system.