A system and a method for therapeutic treatment of biological tissue using weak magnetic fields. In accordance with one embodiment, the system comprises: a magnetic field transducer for transducing electrical currents into magnetic fields; a sheet or disk made of high-permeability material and disposed on one side of the magnetic field transducer, but removable therefrom; and a current source coupled to the magnetic field transducer for supplying electrical current thereto. A magnetic beam produced by the interaction of the sheet of high-permeability material with a magnetic field produced by the magnetic field transducer has a profile which is a function of the composition, geometry and thickness of the high-permeability material. Preferably the high-permeability material has a relative permeability value greater than 10,000.