Investigators in population-based studies confront unique ethical challenges due to the community context of their research, their methods of inquiry, and the implications of their findings for social groups. Issues surrounding requirements for informed consent, the protection of privacy and confidentiality, and relationships between investigators and participants take on greater complexity and have significance beyond the individual research subject. In this paper, ethical challenges associated with community-based epidemiological research are briefly examined. We argue that ethically responsible population-based studies must seriously consider community needs and priorities and that researchers should work collaboratively with local populations to implement study goals. Strategies that promote respect for populations in community-based studies are outlined. These include community participation in research development, implementation and interpretation; adequate provision of information about study objectives to community members; and systematic feedback of study results.