Abstract: Ingestible electronic sensors are a promising technology for improving health outcomes that may, for example, be useful in monitoring and promoting the taking of medication. However, these sensors also raise ethical and legal challenges that need to be considered by all stakeholders—notably, the creators of such products—at the earliest stages of the development process. Here, we examine selected ethical and legal issues related to ingestible electronic sensors. We first briefly describe sensors that are already available on the US and European markets as well as potential future sensor combinations. We then focus on ethical aspects, discussing patient, provider, and social issues. Finally, we provide a comparative analysis of legal regulation of ingestible electronic sensors in the US and Europe.