The primary objective of this research is to explore the determinants of compliance to iron supplement medication among a sample of pregnant women. The data is based on a larger research project on Nutritional Anemia collected by the Nutrition Center of the Philippines, from 1980 to 1982. The focus of analysis is on compliance as a dependent variable. Also, three sets of factors are used to explain compliance behavior. These are: socio-demographic, treatment, and social psychological factors. The sample consists of 377 pregnant women who were interviewed to explore the research problem. Data are obtained from a survey, and are analyzed using zero-order correlations and multiple regression techniques. Results of the zero-order correlation analysis show that the socio-demographic and treatment factors have weak relationships with compliance rate. Moreover, among the social-psychological factors, three are found to have significant positive correlations with compliance rate; and these are, folk health beliefs, perceived knowledge about the benefits of vitamins, and mothers‘ health practices. The results of the multiple regression analysis indicate that, with controls, all the potential determinants are not significantly related to compliance rate. The study results are then evaluated in the light of the literature on compliance in the United States. A compliance model is then suggested which serves as a guideline for future research. However, even with the establishment of this compliance model, a question concerning the operationalization of the variables remains. Some suggestions on measures of the variables are provided. / Master of Science