Radiative Corrections to $W$ Pair Production at High Energies

Radiative Corrections to $W$ Pair Production and effects of finite width of the $W$ bosons are studied using the Monte Carlo {\tt WOPPER}. As an example the influence of QED radiative corrections on the reconstruction of the $W$ helicities at LEP 200 and a future 500 GeV $e^{+}{e}^{-}$ collider is discussed.