The objective of this article is to investigate the relationship between the utilization of free adult preventive care services and subsequent utilization of inpatient services among elderly people under the National Health Insurance program in Taiwan. The study used secondary data from the 2005 Taiwan National Health Interview Survey and claim data from the 2006 Taiwan National Health Insurance Research Database for the elderly aged 65 or over. A bivariate probit model was used to avoid the possible endogeneity in individuals' utilization of free adult preventive care and inpatient services. This study finds that, when individuals had utilized the preventive care services in 2005, the probability that they utilized inpatient services in 2006 was significantly reduced by 13.89%. The findings of this study may provide a good reference for policy makers to guide the efficient allocation of medical resources through the continuous promotion of free adult preventive care services under the National Health Insurance program.