Using virtual worlds as media for learning and teaching gives rise to the potential for many unique ethical problems. Some of these arise due to the nature of the engagement with these virtual worlds, in which the students create a virtual representation, called an avatar, which may enable a sense of embodiment, and hence exposure, within the world. Many of these environments are also not dedicated to learning and teaching but are social worlds inhabited by communities of users; learning and teaching activities may therefore more resemble those of a field trip than a classroom experience and consequently the potential for conflict and anxiety between students and this wider community. This article explores the various ethical issues of learning and teaching in virtual worlds, and draws on the examples of two case studies to illustrate these issues with students' comments. The authors then offer their own personal responses to the ethical issues raised; rather than offering solutions the paper acknowledges that these issues are ones that need further reflection and consensus-building for the educational community. (Contains 5 notes.)