We solve the diffusion equation in the normal metal of ferromagnet-normal m
etal-ferromagnet (F-N-F) systems with non-collinear magnetizations. It is s
hown that the total conductance of the system in the presence of a magnetic
field can be asymmetric with respect to time reversal. This asymmetry is a
ssociated with precession processes described by the imaginary part of the
recently introduced mixing conductance. (C) 2001 Elsevier Science B.V. All
rights reserved.