Purpose: The purpose of this study was to investigate the effects of copayments for doctor visits and prescription drugs on health services utilization in the Type I Medicaid beneficiaries in Korea. Method: This study examined data from the 2007 survey on Health Services Use and Health Status of Medicaid Beneficiaries performed by the Ministry for Health Welfare and Family Affairs. To analyze these sample survey data, the SURVEYFREQ, SURVEYMEANS, and SURVEYREG procedures which incorporate the sample design into the analyses were used. Results: Findings of this study indicate that copayments for doctor visits and prescription drugs of Medicaid Type I beneficiaries have cut overall medical costs. However, although results should be interpreted very carefully because of the relatively low $R^2$, copayments have cut more health services utilization of people who need more health services because of their complex diseases and disability. In addition, besides copayment, several factors are affecting differences in health services utilization before and after copayments implementation. Conclusion: These results highlight the need to examine the effects of copayments more thoroughly according to the kinds of disease, the severity of disease, and the level of copayment.