Mobile health (mHealth) is rapidly being implemented and changing our ways of doing, understanding and organising healthcare. mHealth includes wearable devices as well as apps that track fitness, offer wellness programmes or provide tools to manage chronic conditions. According to industry and policy makers, these systems offer efficient and cost-effective solutions for disease prevention and self-management. While this development raises many ethically relevant questions, so far mHealth has received only little attention in medical ethics. This paper provides an overview of bioethical issues raised by mHealth and aims to draw scholarly attention to the ethical significance of its promises and challenges. We show that the overly positive promises of mHealth need to be nuanced and their desirability critically assessed. Finally, we offer suggestions to bioethicists to engage with this emerging trend in healthcare to develop mHealth to its best potential in a morally sound way.