This chapter discusses the main research ethical concerns that arise in internet research and reviews existing research ethical guidance in the Irish context in relation to its application to internet research. The chapter begins with a brief outline of high profile cases in the early history of the internet that highlighted specific emerging ethical concerns regarding the new medium and the first development of ethical guidance in this context. Important research ethical concerns in internet research are then presented. These include: (i) understanding the specific relationship between researchers, participants and the online materials, and the ethical significance of contributors' potential lack of awareness of research conducted on their online interactions, (ii) clarifying privacy expectations and ethical requirements regarding the access to and use of online materials, (iii) implementing ethically appropriate consent processes in the online medium, (iv) doing justice to confidentiality, anonymity and data protection requirements and (v) clarifying vulnerability of participants, and potential risks and benefits arising from research participation. In the final part of the chapter existing Irish research ethical guidance documents are reviewed in relation to the relevance of their guidance for the conduct of internet research. [For the complete book, "Internet Research, Theory, and Practice: Perspectives from Ireland," see ED575997.]