an electro - therapy apparatus and method for providing therapeutic electric current to a treatment site of a patient , having means for providing two oscillating or pulsing electric alternating currents , of frequencies which differ from each other by as little as 1 hz and up to about 250 hz , but each being of frequency at least about 1 khz . the apparatus and method requires only one feed electrode adapted to feed the electric currents to selected feed sites on or beneath the epidermal or mucous surface of the patient , and only one return electrode adapted to be positioned on or beneath the epidermal or mucous surface of the patient , locally to the treatment site . the apparatus includes a feedback subsystem to detect impedance changes in the patient and accordingly adjust the output of the apparatus .