With remarkable advances in medicine, the total bill of health care expenditure in Korea continues to rise at an ever increasing rate. Under the health insurance, however, to provide the appropriate medical care in limited resources and finite economy, efficient ways of approach to medical services are needed. One of them is to weigh the justification of sophisticated application of medical practice, taking into consideration both cost and effectiveness. Sice medical services have indispensable relation to health insurance, both sides should try to make good companion in order to accomplish the ultimate goal of health improvement and everythhing about health insurance. Especially the basic principles of medical fees review must be kept in mind.