Background. Ethics are rules or standards governing the conduct of a person or members of a profession. Medical research must be regulated to ensure that fundamental human rights are not breached in the quest for knowledge. Nigeria had no laws or specific guidelines to regulate health research until 2007, when a national regulatory body, the National Health Research Ethics Committee, was established. Its function is to ensure ethical conduct in research and to accredit institutional and state health research ethics committees.Objective. (...) To document the current role of HRECs in the ethical practice of health research in Nigeria, 4 years after the establishment of the NHREC.Methods. Functioning of the HRECs was evaluated via interviews of 14 members of state and institutional HRECs chosen from selected geopolitical zones of the country.Results. The HRECs surveyed had between nine and 15 members, with more males than females. Review meetings were held only occasionally owing to the competing interests of members, who receive no incentives for participation, and poor funding. Scientific and ethical reviews are conducted together by the same committee, but few members of the HRECs are trained in research ethics. Monitoring of research after approval is poor.Conclusion. Nigeria now has about 30 institutional HRECs, but their functioning is hampered by a shortage of both money and qualified individuals to serve on them. (shrink)