A multi-purpose, implantable stimulator for use in an FES system includes a housing, implantable into a patient's body. The housing contains a receiving device and a control unit, the control unit receiving signals from the receiving device which, in turn, receives signals transcutaneously from a controller arranged externally of the patient's body. A plurality of leads extend from the housing, the leads being arranged in separate bundles of discrete leads, each bundle being associated with a particular site of the patient's body.