A prosthetic leg having an electronically controlled regenerative prosthetic knee. In certain embodiments of the present invention the knee may be passive, whereby it is used only to generate electrical energy. In other embodiments, the knee may be active, whereby it can be used to assist with or completely control gait, as well as to generate electrical energy. The knee makes use of an actuator motor/generator to control gait and/or to generate electrical energy. An electronic control system is provided to control overall operation of the prosthetic leg, to distribute generated electrical energy, and to transfer excess electrical energy to one or more storage devices for later use. A prosthetic leg of the present invention having an active prosthetic knee may be especially helpful in assisting an amputee with activities that impart a high torque load to the knee joint.