Because operationg room time is one of the most expensive hospital resources, cancellation of a planned surgery is a wasteful expenditure of specialized human manpower and other medical resources. To decrease the rate of cancellation, we performed this prospective study about patients who planned elective surgery under general or regional anesthesia frome September 1, 1990 to December 31, 1990 in the operating room of Yeungnam University Hospital. Daily, the total number of planned surgeries and cancelled patients were recorded, and the most important reasons for cancelling by an individual patient were also recorded. The results were as follows: 1)The total number of planned elective surgeries was 3,102 patients and total number of cancelled patients was 502 patients. Thus the mean rate of cancellation was 16.2%. 2)The highest rate of cancellation was in October(21.2%), and the departmental variation was hte highest rate in dental(37.5%) and the lowest rate in the ophthalmic department(8.6%). 4) The reason of cancellation were as follows: combined systemic diseases or abnormal laboratory findings(42.4%) were most common, and the next was no admission(14.5%), heavy schedule or deficinecy of operating room(10.3%), refusal of operation(8.6%), insufficinet patient preparation(7.8%), and affairs of operator or department(7.4%), and others. As a result of this study, there are several ways to decrease the cancellation rate in operating room of yeungnam University Hospital. The first is a careful preoperative evaluation of patient's physical status and results of labaratory examination before hospitalization, and then the common practice of outpatient surgery, appropriate plan of overall elective operation, reasonable management of an operating room, and good relationships between the individual department, especially surgeons and concultant. If we follow the above mentioned ways, disruptions of the surgical schedules may be avoided and a more economical management of the operationg room is possible.