Italian version of Appropriateness Evaluation Protocol (AEP) is a tool for evaluating the appropriateness of hospitalization for acute patients. In particular, it aims to verify and quantify the reasons of appropriateness associated to the day of admission and the single days of hospital stay. The aim of the present paper is to evaluate the appropriateness of ordinary, 2-3 days lasting, hospital admissions within an university hospital. We examined a sample of 518 hospital admissions: 370 admissions (71%) lasting 2 days, and 148 admissions (29%) lasting 3 days. Results analysis showed different levels of appropriateness between the 2-days and the 3-days admissions: the appropriate admissions were 18% in the sample of the 2-days admissions and 38% in the sample of 3-days admissions. Most inappropriate days of admission and stay in hospital are due to attended or to the execution of diagnostic procedures. In order to evaluate accuracy by means of AEP methodology, it is necessary to improve the quality of medical documentation using standardized medical records. AEP, in the framework of the continuous quality improvement, is a valid tool to reorganise health care processes.