Abstract: This study assesses the perceived level of Open Access (OA) awareness, challenges, and opportunities in context of university libraries of Pakistan. The differences between public and private sector university libraries in terms of their awareness, challenges and opportunities were also analyzed in this study. Survey research design, based on a structured questionnaire, was employed to meet the objectives of the study. The population of the study was libraries of Higher Education Commission of Pakistan (HEC) recognized universities located in Punjab and Islamabad (Pakistan). The findings revealed that majority of university libraries were fully aware of HEC-National Digital Library (NDL) OA resources, OA journals, and Pakistan Research Repository, whereas, somewhat aware of Budapest OA Initiative, and Diamond OA Model. Lack of additional resources (staff, time, efforts), unreliability of OA information resources, and inadequate tools and infrastructure were identified as top challenges. However, free access, increase in library value, and fulfilling users need with shrinking budget were top three identified opportunities. The study did not find any significant statistically difference between public and private university libraries in terms of their level of awareness, perceived challenges and opportunities. This study is administered in institutional context and fills the literature gap.