Diarrhea is a leading cause of pediatric morbidity and mortality in the Dominican Republic. A potential policy option for reducing the burden of this disease would be to utilize the public and private sector health resources of the country in a co-ordinated fashion. To do so requires an understanding of the determinants of health services' utilization for this disease. This study examines the predictors of (a) health services' utilization, and (b) public vs. private sector use, for diarrhea in the under-five population in the Dominican Republic. The DHS-2 dataset (1991) was utilized for analysis. Logistic regression models for predicting use and non-use, and for predicting private vs. public sector use were constructed. Age, nutritional status, rural location, higher maternal education and duration of illness greater than 2 days were significant predictors of use of health services. Nutritional status, private insurance and higher maternal education were found to be significant predictors of private sector utilization rather than public sector utilization. Such disease-specific sector utilization should be kept in mind when attempts are made to adjust the public/private mix in health sector reform.