The Internet offers many new opportunities for behavioral researchers to conduct quantitative and qualitative research. Although the ethical guidelines of the American Psychological Association generalize, in part, to research conducted through the Internet, several matters related to Internet research require further analysis. This article reviews several fundamental ethical issues related to Internet research, namely the preservation of privacy, the issuance of informed consent, the use of deception and false feedback, and research methods. In essence, the Internet offers unique challenges to behavioral researchers. Among these are the need to better define the distinction between private and public behavior performed through the Internet, ensure mechanisms for obtaining valid informed consent from participants and performing debriefing exercises, and verify the validity of data collected through the Internet.