Objective: The development of evidence-based health policy is challenging. This study has attempted to identify some of the underpinning factors that promote the development of evidence based health policy. Methods: A preliminary systematic literature review of published reviews with "evidence based health policy" in their title was conducted using PubMed as a search engine. The identified papers were critically analysed using a "realist review" method, driven by the question "What works for whom in what circumstances and in what respects?". Results: Eight published reviews met the search criteria. Following the "realist review", six factors that underpin the development of evidence-based health policy were identified. They are: (i) the importance and value of having multi-disciplinary teams; (ii) the need to have a broad evidence base to draw upon; (iii) the circular relationship between research and policy; (iv) the need for policy implementation to be locally sensitive; (v) the benefit of stakeholder involvement; (vi) support by the national Government. Conclusion: The six factors identified provide a framework for consideration for those whose work involves evidence-based health policy development. As a corollary, the failure to satisfy these factors in evidence-based health policy development may lead to resistance to policy change and further work is warranted. (Contains 1 table and 1 note.)