Abstract: A method of treating animal tissue with a time-varying, magnetic field and a device for producing such a field wherein a substantially unipolar, rectangular electro-magnetic treatment signal having pulses of a predetermined frequency and amplitude is generated. The signal is transmitted to a coil wherein it induces a magnetic flux. The magnetic flux so produced is applied to a treatment site to promote healing of tissue. A biasing circuit is provided in the device to prevent the occurrence of a reverse polarity pulse upon the fall of the magnetic flux induced by the fall of the generated pulse and to diminish high frequency ringing at the beginning of a treatment signal.