OBJECTIVES: Many factors influence pharmaceutical reimbursement decisions. This study aims to determine the influence of factors considered in the evaluation of pharmaceuticals on the reimbursement decisions of government funded bodies in OECD countries. METHODS: A search of MEDLINE, EMBASE, EconLit, Health Management Information Consortium, NHS EED and REPEC Economic working papers until July 2010 was conducted. A hand search of the International Journal of Technology Assessment in Health Care was undertaken (1990-2010). The following study designs were eligible: experimental, quasi-experimental, retrospective, prospective, case series and surveys or questionnaires design. The influential factors were reviewed across and within OECD countries. RESULTS: The search identified 12 quantitative studies and 23 qualitative studies. The quantitative studies considered the correlation between factors and decisions either through regression analysis of retrospective decisions or discrete choice experiments. Cost-effectiveness was found to be consistently influential for reimbursement decision-making in Australia, England, Canada and the Netherlands. There was variation in the definition of clinical considerations and other factors in studies conducted in countries. This limited comparability within and across countries. Studies reported mixed evidence of the influence of the quality, quantity and type of clinical evidence, robustness of economic models, sensitivity analysis, budget impact, lack of alternative therapy and severity of disease on reimbursement decisions. Qualitative studies reported narrative descriptions, case studies and interviews with decision-makers. These studies supported the influence of cost-effectiveness found in the quantitative evidence. They additionally described the influence of the composition of the decision panel, committee deliberations, stakeholder involvement and lobbying on decisions. CONCLUSIONS: There is limited evidence on the influence of evaluation factors on reimbursement decisions in a few OECD countries with established reimbursement processes. Wider investigation of the factors influential in other countries would allow comparison of the similarities and differences across OECD countries.