  We study the quantum effects on vector-boson pair production in e^+e^-
annihilation induced by the sleptons and squarks of the minimal supersymmetric
extension of the standard model (MSSM) in the one-loop approximation. We list
full analytic results, and quantitatively analyze the resulting deviation from
the standard-model prediction of e^+e^- -> W^+W^- for the supergravity-inspired
MSSM. The latter can be rendered small throughout the whole parameter space by
an appropriate choice of renormalization scheme.
