We investigated the effect of the light fermion masses on cross sectio
ns for e(+)e(-) --> 4 fermions in the fermion loop scheme defined by W
. Beenakker et al. [NIKHEF-96-031 (1996), hep/ph-9612260], and approxi
mations to it. The effects are found to be very small, except of cours
e in the collinear region of single W boson production where the elect
ron mass acts as the cut-off. (C) 1997 Published by Elsevier Science B
.V.