Tertiary been increasing rapidly. There has been shortage of beds in hospitals and effective management of beds had to b considered. For the efficient utilization of the exsisting hospital beds, bed turnover rate ha to be high and their length of stay in hospital has to be shortened. The sample of this study was in-patients admitted in 13 clinical departments of a tertiar hospital in Wonju. Daily medical fees through length of stay in hospital were observed an we analyzed the increase of hospital revenues per bed for the shortening of length of stay. The results of the analysis were as follows: 1. The average length of stay by dept. was 11.0 in dept. of internal medicine. 12.4 in dept. of general surgery, 7.1 in dept. of gynecoloty, 6.8 in dept. of pediatrics, 26.1 in dept. of nervous surgery, 21.6 in dept. of orthopedic surgery, 25.5 in dept. of plastic sersury, 7.6 in dept. of ophthalmology, 7.1 in dept. of E.N.T, 8.1 in dept. dermatoloty, 9.0 in dept. urology. 2. The trend of daily medical fees of in-patients was the highest from the first day to the third day. Because most necessary examination and various treatment or operation took place in these period. 3. The estimative model for medical fees by the length of stay at each clinical department was inferred. 4. The increased revenue per bed by shortening the length of stay was calculated by the estimative model. Shortening one day would increase 305,999 thousand won in dept. of internal medicine 232,138 thousand won in dept. of general surgery., 177,795 thousand won in dept. of gynecology medicine, 69,031 thousand won in dept. of pediatrics 360,381 thousand won in dept. of nervous surgery 211.339 thousand won in dept. of orthopedic surgery, 100,249 thousand won in dept of plastic surgery, 10,569 thousand won in dept. of ophthalmology -814,122 thousand won in dept. of E.N.T, 1,582 thousand won in dept. of dermatology, -5,821 thousand won in dept. of urology. It is expected that they can improve their profitability by shortening the length of stay of the in-patients.