The role of the Research Ethics Committee (REC) in the design, conduct and dissemination of scientific research is still evolving and many important questions remain unanswered. Hence, the aim of this paper is to address some of the uncertainty that exists around the role and responsibilities of RECs and to discuss some of the controversy that exists over the criteria that RECs should follow when evaluating a research proposal. The discussion is organised around five of the major roles currently performed (...) by RECs when assessing proposals in the biomedical sciences. It will be shown that these five roles need to be critically evaluated and reassessed. The five roles addressed are: assessing the legitimacy and validity of the informed consent process, second, conducting a comprehensive risk/benefit analysis, third, assessing the validity of a research proposal, fourth, ensuring that researchers observe the social norms, values, customs, traditions and laws that prevail in the community or jurisdiction in which the research will be conducted and finally, monitoring the research project as it unfolds and providing an ongoing advisory and consultancy service to both new and experienced researchers. In reassessing the role of the REC, this paper concludes with a set of general recommendations for RECs. These provide some guidance on the minimum criteria that should be followed when RECs evaluate proposals. These guidelines will be beneficial for new and experienced members of REC, and will help to make the process a more objective, efficient and standardised process. The guidelines will also be beneficial for researchers in the biomedical sciences who are preparing proposals for ethical review. (shrink)