A bioelectronic device comprising an enzymatic biofuel cell (GBFC) connected to a wireless tele-transmission system was implanted in a rabbit and its function was monitored and controlled in vivo for a period of 2 months. After the 18th day of implantation, the tele-transmission system was used to wirelessly charge and discharge the operational GBFC in vivo through a 100 kU load for 30 min each day. For a further 16 days of operation, the GBFC delivered 16 mW mL À1 continuously during each 30 min discharge each day for 16 days. At the end of the 2 month period of implantation the power output had diminished, which was most likely due to an inflammatory process. Our results also indicate that the duration of operational activity is increased by optimizing the interface between the GBFC and the body to minimize inflammatory processes and biofouling. These data provide a significant advance in the achievable output from a GBFC that is implanted in a mammal, and importantly provide a basis upon which to further develop stable implantable biofuel cells. Improving the in vivo performance of an implanted GBFC includes the development of biocompatible diffusing polymers to act as buffering diffusion barriers.