The pattern of use of emergency department of hospitals is on the agenda of policy makers at national, regional and local level. It is still difficult to achieve a balance between the claim for improving the accessibility in order to allow people in need to receive this level of care and the possible its inappropriate use. The triage procedure offers the possibility to assess priorities because the "white codex" identifies those whose access to emergency department could potentially be diverted to an other level of care. The use of the Emergency Department is studied in an affluent area of Northern Italy using an "ad hoc" tool and data linkage in order to describe the process and its possible failures. The results are aimed to give decision makers the opportunity to start addressing these issues on sounder bases particularly as far as triage based assessment is concerned.