To identify the changes in professional services pattern after introducing the deligated system of claims review started in 1982, a university hospital under this system was examined. For comparison, claims of the hospital to Federation of Korean Medical Insurance Societies, where this system is not accepted, were reviewed. A total of 600 cases each were studied operated at the Departments of General Surgery & Orthopedic Surgery in 1981 and 1983. The results are summarized as follow: 1. Percentages of hospital charges for basic care was decreased by 10.2% and that for medical service increased by 8.4% in 1983. 2. After the introduction of the deligated review system, percentages of cutting off the claims was decreased by 12.4% for basic care and increased by 3.8% for medical services. 3. Percentage of testing liver function, and the frequency of administering high cost intravenous fluid injection, applicating Robinul as anesthetic premedication were decreased respectively after introducting the deligated services system.