The study examined the impact of open educational resources (OER) on the cost and quality of course materials in postgraduate distance education courses at the University of the Philippines Open University (UPOU). 48 courses from 3 disciplines - Education, Health, and Development Studies - were reviewed. The results showed that OER use varied by discipline, with Health courses using OER most at 50% of modules on average. Students and faculty generally perceived that OER-using courses matched learning objectives and topics. In Education specifically, OER were seen as appropriate to course level and relevant to topics. In Health, learning resources were highly rated in terms of sufficiency, relevance, and accuracy. Across disciplines, learning activities using OER were