Different studies rate the proportional number of visits unsuited to the HER services at 20%-80% of all. This wide range is due, in good part, to no consensus existing as to the definition of the term "emergency" and the ideal degree of assistance for dealing with each possible situation which leads to the use of subjective judgments for evaluating unsuitability. The purpose of this study is that of developing and validating an objective tools for pinpointing unsuitable hospital emergencies. Based on a conceptual framework which included as dimensions the seriousness of the clinical condition of the patient in question, the intensity of the services rendered and some situations which would warrant spontaneous visits being suitable, the Hospital Emergency Suitability Protocol (HESP), a tool entailing explicit criteria for assessing the suitability of the visits to the HER's, and a random sample of 100 emergency room clinical histories, the reliability thereof of observers on an individual and group basis and the validity of judgment and predictive validity thereof as regarding the opinion of experts having been analyzed. The HESP revealed itself to provide an excellent reliability rate of observers on an individual and group basis (indexes of agreement fond of 99%-100%; kappa statistic of 0.97-1.00), and judgment validity on the borderline between moderate and low (index of agreement found of 68%, kappa statistic 0.39). This low level of agreement is due to the fact that the HESP functions like a highly specific (the inappropriate cases accord to the clinical judgment are evaluated as inappropriate) yet not highly sensitive tool (solely 59% of the cases which the HESP considered to be suitable were evaluated as such by the clinical judgments). The HESP acts as a highly reliable tool capable of pinpointing the most clearly unsuitable fraction of the inappropriate visits to the HER's. These characteristics make it useful for drawing comparisons among hospitals and for long-range follow-up or monitoring of actions for lowering the percentages of unsuitable use.