Increasingly, US-sponsored research is carried out in developing countries, but how US Institutional Review Boards (IRBs) approach the challenges they then face is unclear.METHODS: I conducted in-depth interviews of about 2 hours each, with 46 IRB chairs, directors, administrators and members. I contacted the leadership of 60 IRBs in the United States (US) (every fourth one in the list of the top 240 institutions by National Institutes of Health (NIH) funding), and interviewed IRB leaders from 34 (55%).RESULTS: US IRBs face (...) ethical and logistical challenges in interpreting and applying principles and regulations in developing countries, given economic and health disparities, and limited contextual knowledge. These IRBs perceive wide variations in developing world IRBs/RECs' quality, resources and training; and health systems in some countries may have long-standing practices of corruption. These US IRBs often know little of local contexts, regulations and standards of care, and struggle with understandings of other cultures' differing views of autonomy, and risks and benefits of daily life. US IRBs thus face difficult decisions, including how to interpret principles, how much to pay subjects and how much sustainability to require from researchers. IRB responses and solutions include trying to maintain higher standards for developing world research, obtain cultural expertise, build IRB infrastructure abroad, communicate with foreign IRBs, and ‘negotiate’ for maximum benefits for participants and fearing ‘worst-case scenarios’.CONCLUSIONS: US and foreign IRBs confront a series of tensions and dilemmas in reviewing developing world research. These data have important implications for increased education of IRBs/RECs and researchers in the US and abroad, and for research and practice. (shrink)