|The purpose of this study was to determine the level of appropriateness in hospital stays and factors influencing inappropriate hospital stays. The study was conducted at fifteen general care units in a tertiary university hospital. Appropriateness of hospital stay was assessed using Appropriateness Evaluation Protocol by trained head nurses. The total of 447 patient records were reviewed. Among them, 352 patient data were included in the final data set. A unit of observation was patient day. A rate of appropriate hospital stay was calculated per patient as a unit of analysis. Multiple regression analysis was performed to determine the factors affecting inappropriate hospital stay. The eighty-three percent (2030/2651) of hospital stays were evaluated as appropriate. There were significant differences in appropriateness of hospital stay according to patient`s age, type of health insurance, medical specialty, and length of stay(p<0.05). In the multiple regression analysis, medical speciality was the most significant factor to predict the inappropriate hospital stay. The study showed a substantial proportion of hospital stay was found to inappropriate. Level of appropriateness was significantly different from medical specialty. Inter-departmental approach should be required to coordinate and improve appropriate resource utilization.