A closed coupled identification system for verifying the identity of an animal, object or other thing, has a probe including a circuit adapted to be connected to a source of alternating current and a separate, preferably miniature, circuit adapted to be implanted within or attached to the animal, object or thing. The probe circuit is held adjacent the implanted circuit for mutually inductively coupling the circuits so that a load applied to the implanted circuit has an effect on the current in the probe circuit. A programmable load is included in the implanted circuit, along with means for sequentially connecting and disconnecting the load to and from the implanted circuit in response to alternating current cycles in the probe circuit, according to a predetermined code program. A signal is derived from the probe circuit having a waveform corresponding to the coded program in the implant circuit. Further means are employed to decode the waveform and to display a number or other representation corresponding to the code program and indicating the identity of the implanted circuit, and, hence of the animal, object or thing.