It has been carried out a survey to evaluate the appropriateness of hospital stay in a university hospital. The aims of the study were: to determine the amount of inappropriate hospital admissions and inappropriate days of stay in relation to either wards and characteristics of admission; to analyse the reasons for inappropriate patient stay. A randomised sample stratified by ward of discharge of 224 medical records were analysed using the Italian version of the Appropriateness Evaluation Protocol. 37.9% of the hospital admissions and 18.9% of hospitalisation days were judged to be inappropriate. The main reasons for categorising an admission or a day of stay as inappropriate were a) delay in performing elective surgery procedures; b) that the patient's problem could be treated on an outpatient basis; c) delay in performing diagnostic examinations. The univariate statistical analysis showed an association between appropriateness of hospital stay and gender age, ward of discharge, length of hospital stay and DRG type (medical/surgical). The study highlights a lower level of inappropriateness compared to the results of other investigations. Hints were also identified for achieving an improved efficiency at hospital level.