  We present a short comment on resummation of double-logarithmic (DL)
contributions to decays of W and Z -bosons into charged fermion pairs. We show
that resummation of DL corrections to the Z -boson decay leads to standard
Sudakov form factor with the negative exponent independently of the boson is
on-shell or off-shell. In contrast, the Sudakov exponent for the W - decay is
negative (positive) when the W-boson is on-shell (off-shell). In this
connection we consider applicability of the Dispersion Relations to the case
when the imaginary parts contain infrared-divergent contributions.
