Conflicts have arisen in international research when countries in which research is being carried out lack the ethical rules or mechanisms for review employed in the United States and Europe. It is objected that a requirement to adhere to regulations promulgated by the US government constitutes “ethical imperialism.” But if researchers in some countries need not be bound by ethical standards widely accepted in the conduct of research, it could open the door to an ethical relativism allowing virtually any standard a country desires to accept. One example is the variations in informed consent, especially in countries that accord lesser importance to the individual than do the US and Europe. A recent controversy centered on a series of placebo-controlled, HIV/AIDS trials sponsored by the United States and conducted in several developing countries. These trials could not ethically be carried out in the United States because a proven effective treatment exists. Attempts to avoid similar controversies in forthcoming HIV/AIDS vaccine trials have been initiated by the joint United Nations AIDS program, with a process of regional consultations in the countries where the research will be conducted.