This study seeks to provide a framework for understanding differential access to medical care. The framework is provided by Anderson Model, a model of health services utilization which suggests a sequence of predisposing, enabling, illness-morbidity characteristics that determine the number of times people will visit a physician. The framework in this study is composed of two models, one is for Adults and the other is for Non-Adults. Models are operationalized using stepwise multiple regression analysis and path analysis. The data come from a national health survey conducted in 1983. The findings of the analysis can be summarized as follows : First, the causal models used in this study are able to explain only a small amount of the variance in medical care utilization(Adjusted $R^2$ is .144 in the Model for Adults and .243 in that for Non-Adults). This finding suggests that we reconsider the utility of such existing model using the predisposing, enabling, and illness-morbidity characteristics in light of their poor correspondence with these data. Second, while small amount of the valiance in medical care utilization is explained, most of the explained variance is due to the illness-morbidity characteristics. The path coefficients of study variables except illness-morbidity variables show these characteristics to be substantially unrelated to medical care utilization, and the indirect effects of the predisposing and edabling characteristics on medical care utilization are also negligible. This casts doubt on the importance of the predisposing and enabling characteristics in explaining medical care utilization. Third, among the predisposing and enabling characteristics, Medical Security variable is the only one having significant direct effect on medical care utilization in both models for Adults and for Non-Adults. Fourth, the amount of the variance explained in the Model for Non-Adults is more than in the Model for Adults. This suggests that medical care utilization of adults is more influenced by behavioral factors than that of children.