Objective : To analyze the factors affecting the participation rate in the health screening program of medical insurance. Method : We investigated the factors associated with the participation rate in the health screening program in Korea. Data were collected at the aggregate level from 145 employee health insurance societies and 227 self-employed health insurance societies from 1995 to 1997 Data were also collected at the individual level from four health insurance societies. This study hypothesized that the participation rate of the health screening program was related to 1) the characteristics of its members and the size of the health insurance society; 2) the specifications of the health screening program; 3) the venue of the health screening institution and the interests of individuals in the health screening program; and 4) the activities of the health insurance society. We used bivariate and multiple regression models to examine the factors on the participation rate of the health screening program. Results : First, in the case of dependents of on employee health insurance society, the ratio of dependents 40 years old and over, the average monthly contribution per household, the interest and satisfaction level of individuals in health screening, and the level of refunds for over-payment were all associated with the participation rate in the health screening program, accounting for 54.4% of the participation rate. Second, in case of those insured by the self-employed health insurance society, the interest and satisfaction level of individuals in health screening, the level of refunds for over-payment, and the performance level of on-the-spot health screening were statistically significant, accounting for 40.1% of the participation rate. Conclusion : The factors concerning the participation rate in the health screening program of medical insurance, in both a health insurance society and for individuals, were closely related to the age and gender of individuals and household contributions.