Changes in the age distribution of the population and increased prevalence of chronic illnesses, together with a shortage of health professionals and other resources, will increasingly challenge the ability of national healthcare systems to meet rising demand for services. Large-scale use of eHealth and mHealth services enabled by advances in ICT are frequently cited as providing part of the solution to this crisis in future provision. As part of this picture, self-monitoring and remote monitoring of patients, for example by means of smartphone apps and body-worn sensors, is on the way to becoming mainstream. In future, each individual’s personal health system may be able to access a large number of devices, including sensors embedded in the environment as well as in-body smart medical implants, in order to provide (semi-)autonomous health-related services to the user. This article presents some examples of mHealth systems based on emerging technologies, including body area networks (BANs), wireless and mobile technologies, miniature body-worn sensors and distributed decision support. Applications are described in the areas of management of chronic illnesses and management of (large- scale) emergency situations. In the latter setting BANs form part of an advanced ICT system proposed for future major incident management; including BANs for monitoring casualties and emergency services personnel during first response. Some challenges and possibilities arising from current and future emerging mHealth technologies, and the question of how emergence theory might have a bearing on understanding these challenges, is discussed here