In this work developments are presented, which shift the technological frontiers in the field of powering and data communication for wearable and implantable medical systems and which may help the introduction of ambulatory monitoring and ambient intelligence in the near future. Inductive power transmission is proposed as a way to provide power to wearable and implantable electronic devices. The design trajectory of an inductive link is covered and optimization methods are proposed and successfully illustrated with an example. Next, the integration of bidirectional data transmission in the inductive link is treated. The major contribution is the use of one single inductive link for both the transmission of power and the bidirectional transmission of data. This drastically increases the ease of use of the system and decreases the dimensions of the secondary (implantable) circuit, as only on set of antennae is used. Two examples are the instrumentation of a hip prosthesis for the monitoring of early loosening in orthopaedics, and a smart suit for the monitoring of children in a hospital environment, containing dedicated textile sensors for respiration and ECG.