  We report on the calculation of the next-to-leading order QCD corrections to
the production of W-boson pairs in association with a hard jet at the Tevatron
and the LHC, which is an important source of background for Higgs and
new-physics searches. The corrections stabilize the leading-order prediction
for the cross section considerably, in particular if a veto against the
emission of a second hard jet is applied.
