  QCD one-loop corrections to the full gauge invariant set of electroweak
diagrams describing the hadronic process $e^+ e^- \to u~\bar d~s~\bar c$ are
computed. Four-jet shape variables for $WW$ events are studied at
next-to-leading order and the effects of QCD corrections on the determination
of the $W$--mass in the hadronic channel at Lep 2 and NLC is discussed. We
compare the exact calculation with a ``naive''approach to strong radiative
corrections which has been widely used in the literature.
