While accepted as serving an important function to safeguard human subjects, the process of obtaining regulatory approvals to conduct clinical trials is generally regarded as cumbersome and time-consuming. For large multinational trials, U.S. federally sponsored human subject research abroad involves specific U.S. regulatory requirements, in addition to those of the host country, that act as further hurdles. These requirements may include obtaining an Assurance of Protection for Human Subjects from the Office of Human Research Protection of the U.S. Department of Health and Human Services, maintaining specific Ethics Committee/Institutional Review Board (EC/IRB) composition, and incorporating mandated elements in informed consents, all of which may differ from local policies and guidelines. Specific examples of issues that led to delays in regulatory approvals for sites participating in the multinational clinical trial entitled Evaluation of Subcutaneous Proleukin in a Randomized International Trial (ESPRIT) are presented here. While the goal of these requirements is to protect the rights and welfare of human subjects, they may create substantial delays and engender resentment over the notion of lack of respect for individual country sovereignty. Substudies within ESPRIT have been undertaken to obtain feedback from EC/IRB chairpersons, site personnel responsible for processing the required assurances, ESPRIT investigators, and study participants regarding aspects of current U.S. regulatory requirements related to human subject protection and ethical issues in multinational research. The purpose of these substudies is to compare the attitudes and experiences across countries regarding important ethical issues associated with conducting ESPRIT. One objective of the substudies is to gather additional insight to the impact of U.S. regulatory processes. Another is to help to inform the debate about how to best maximize the rights and welfare of clinical trial participants without delaying the initiation of research, while respecting the importance of national sensitivities.