A low magnetic signature motor system (1) comprises a plurality of electric motors (2), a first shield (9) and a second shield (13). The electric motors are arranged with their associated magnetic moments (6, 7) forming a closed loop such that their net external magnetic field (5) is minimized The first shield comprises a material with a high electrical conductivity and substantially surrounds the electric motors such that the a.c. component of the magnetic field is reduced; and the second shield comprises a material with a high magnetic permeability and substantially surrounds the first shield such that the d.c. magnetic field is reduced.