The prospect of using memory modifying technologies raises interesting and important normative concerns. We first point out that those developing desirable memory modifying technologies should keep in mind certain technical and user-limitation issues. We next discuss certain normative issues that the use of these technologies can raise such as truthfulness, appropriate moral reaction, self-knowledge, agency, and moral obligations. Finally, we propose that as long as individuals using these technologies do not harm others and themselves in certain ways, and as long as there is no prima facie duty to retain particular memories, it is up to individuals to determine the permissibility of particular uses of these technologies.