The French studies using the Appropriateness Evaluation Protocol (AEP) were developed within the framework of medical audit by local teams, analysing their own practice, in order to improve the quality of care. Four studies were analysed in this review. They were performed in emergency departments and data were collected concurrently. The reliability and validity of this French version of the AEP was assessed. The high reliability of the AEP was found to be useful to measure trends or differences between groups. The percentages of inappropriate admissions observed in the studies ranged from 18 to 25%. The hypothesis that the rate of inappropriate admissions would be highest among the elderly was not confirmed in Paris. Homelessness was the only social factor related to a high rate of inappropriate admissions in three of the studies. In one study, age and lack of social support were found to be risk factors for inappropriate admissions. The study of the causes of inappropriate admissions was important, since they were to be used as an indicator of systemic problems in the organization of health care delivery. A distinction was made between appropriate and justified admissions on both a systemic and an individual level. In conclusion, AEP was found to be an indicator that was both reliable and useful to identify quality of care problems. Among the factors found to be related to inappropriate admissions, the internal organization of the hospital proved to be one of the main reasons and a target for improvement.