PURPOSE: The purpose of this study is to develop the optimal nursing fee for nurse-midwifery center (MC) in the national health insurance system. METHODS: The three methodologies used to calculate the conversion factors for the MCs in the national health insurance include cost accounting method, sustainable growth rate (SGR) model, and index model. In this study, the macro-economic indicators and the national statistics were used to estimate the conversion factors for the MCs. RESULTS: The optimal nursing fee for the MCs in 2011 was estimated to be an increase of 57.7% by cost accounting analysis, a decrease of 17.1% by SGR model, and a decrease of 16.1% by index model. The results from SGR model and index model could had been biased due to the upswing of medical spendings in the short-term period (2008~2009). A sensitivity analysis of pre-delivery subsidy program for OB & GYN hospitals and clinics showed that the program has substantially diminished the demand for the MC services. CONCLUSION: More reliable methodologies to estimate nursing fees precisely are required to prove the value of nurses' services and a government subsidy program for the MC services should be followed from a social perspective.