The aim of this study is to analyze the variations among hospitals and hospital groups in resource use and procedures of diagnostic and therapeutic process, such as laboratory tests, radiologic examinations, tissue diagnosis, timing of surgery after admission, the time required for operation. The study was performed for five procedures including cesarean section (C/S), appendectomy, cholecystectomy, cataract extraction, and pediatric pneumonia. The 2,316 subjects were selected from medical insurance claims list, and from this list 413 cases were sampled for medical record review. The patterns of resource utilization and process of treatment were described according to hospitals and characteristics of hospital groups. The major results were as follows : 1. The numbers of laboratory and radiologic tests showed significant difference among hospitals and hospital groups. In case of hospital groups, we could find tendencies of more tests with increasing hospital bed size. 2. In general, the proportion of operative cases evaluated by tissue diagnosis postoperatively among all operations ranged from 28.3% to 100%. The proportion varied among hospital groups, of which general hospital A group(more than 15 specialty) showed the highest proportion. 3. Post-admission delay until operation and the time required for operative procedure were not invariable among hospitals and hospital groups. The duration of operation in tertiary hospitals was slightly shorter than general hospitals, with varying statistical significance. We could find that probably there were differences of quality among hospitals in some components of procedures, which suggested that the implementation of quality assurance activities would be mandatory. In this study, we simply described the patterns of resource utilization and some features of clinical process, with institution of the need for advanced studies with in-depth analyses for each component of diagnosis and treatment procedures.