Recentdiscoveries in molecular biology and genetics have made it possible forenvironmental health researchers to examine how genetic characteristics affectresponse to environmental exposures. Understanding such gene–environmentinteractions offers exciting possibilities for the prevention and control ofenvironmentally induced diseases. Despite these potential benefits, thecollection and analysis of genetic information in environmental healthresearch presents many of the same ethical, legal, and social (ELSI)challenges found in other types of genetic research. In this article, wedescribe a number of ELSI challenges in environmental genomic research and theopportunities and responsibilities that accompany thisresearch.