The purpose of this study is to classify elderly patient in long-term care facilities using RUG(Resource Utilization Group)-III. It is designed by measuring patient medical characteristics and medical staff time. Elderly patients are classified into 7 categories by clinical(medical and behavioral) hierarchical typology of patients. Through the tertiary split, all 44 groups are formulated. This classification is explained by each patient resource(staff time) utilization level which is called CMI(Case-Mix Index). Major findings are as follows; 1. The objects in this study were classified into 35 groups out of 44 groups. The most frequent category is clinical complex category(CCC; 38.9%). And extensive service category(ESC; 18.8%), reduced physical function category(RPC; 13.1%), special rehabilitation category(SRC; 12.8%), and impaired cognitive category(ICC; 0.00%) are followed. 2. The mean of total CMI was $1.02{pm}0.36$, ranging from 0.68 to 1.44(1 vs 2.12). The mean of CMI of SRC is only 1.17 which should be the highest. The means of ESC and see are equally 1.20. The means of CMI of CCI, ICC, BPC, and RPC were 0.90, 0.75, 0.83 and 0.96, respectively. 3. The validity of this classification was tested. Trend-test using Regression Analysis was done in the secondary split level. SCC, CCC, ICC, and RPC which covered 68.4% of this research objects showed linear trend of CMI in interim classification. This results were statistically significant. 4. In clinical hierarchy, the trend were showed linearity. But the multiple comparison of categories using Scheffe-test showed that SRC, ESC and see had same level of CMI means and CCC and ICC, too. This results were statistically significant. Classifying elderly patients with RUG-III, the results showed partly linear trend in clinical hierarchy and in interim classification in conclusion. But, in clinical hierarchy, it was failed to show the consistent order of CMI. It can be explained by two reasons. One is that this research subjects were overlapped in each clinical hierarchy group. And the other is that the some of the characteristics for clinical hierarchy is not appropriate for them. For the further study, it needs to have proper sample size and to modify RUG-III to K-RUG to consider our.. medical environment.