INTERNATIONAL COLLABORATORS IN BIOMEDICAL sciences face ethical challenges in the design, review, and conduct of research. Challenges include differences in research ethics capacity, cultural differences in interpretation and application of ethical principles, and cooperation between ethics review boards at collaborating institutions. Indiana University School of Medicine (Indianapolis, USA) and Moi University Faculty of Health Sciences (Eldoret, Kenya) developed a Memorandum of Understanding (MOU) to establish greater cooperation between their ethics review boards, followed by a joint needs assessment to assess barriers to implementing the MOU. Focus groups and interviews at each institution revealed that while each side verbalized understanding and respect for the other's culture, there were misunderstandings deeply rooted in each culture that could potentially derail the collaboration. Although the participants at each university agreed on the major principles and issues in research ethics and on the importance attributed to them, a more in-depth evaluation of the responses revealed important differences. Methods to address these misunderstandings are outlined in the recommended Best Practices.