The purpose of this study is to investigate the effect of Medicaid case management (CM) performed by Medicaid case managers on health management and to examine the overall health care utilization with high risk Medicaid beneficiaries. The subjects involved in this research were 113 Medicaid beneficiaries who were recipients CM in Y-gu between October 1st, 2012 and March 31th, 2013. The results show that there were significant differences in ‘recognition of own disease’, ‘understanding of Medicaid policy’, ‘medication’ and ‘healthy lifestyle’. Also there were significant differences in ‘appropriateness of health utilization’, ‘number of medical institutions’, ‘level of social isolation’ and ‘general health status’. In addition, significant differences were found in Medicaid days, outpatient days, medication days and Medicaid costs. It was found that the Medicaid CM had a positive effect on health care utilization. The study suggests the need of strengthening and diversifying Medicaid CM as well as supporting the management and monitoring after the termination of Medicaid CM.