Translational science is a 21st century mission. Government officials and industry leaders are making huge investments in an attempt to transform more basic science discoveries into therapeutic applications. Scientists and policymakers express great excitement about the medical advances that could come with the current bench-to-bedside campaign.A key step in translational science is the move from animal and other preclinical studies to initial human testing. Researchers ability to predict human effects is limited, and first-in-human tests present significant uncertainty. Participants in this (...) form of research face risks and can experience serious, even lethal, harm. Well-known incidents involving Jolee Mohr and Jesse Gelsinger, as well as subjects in the 2006 study of the investigational agent TGN1412, show the dangers that can arise in early human research.The bench-to-bedside campaign will need many volunteers to participate in early human testing. Investigators and regulators must not allow the policy enthusiasm for translational science to overshadow the commitment to protect human subjects. Participants in exploratory research are diverse and as a group lack characteristics usually associated with vulnerable populations, such as impaired decisional ability or economic or educational disadvantage. (shrink)