We study the effects of radiative corrections and W boson finite width
effects on the energy dependence of the process e+e- --> W+W- --> f1f
2f3f4BAR in the W+W- threshold region. We pay particular attention to
the effect of the W finite width on the Coulomb correction. We present
a ''master'' formula for the cross section which is relevant to a pre
cision determination of M(W) by an energy scan of W+W- production thro
ugh the threshold region.