  We compute the leading QCD corrections to K-Kbar mixing in the supersymmetric
standard model with general soft supersymmetry-breaking parameters. We
construct the \Delta S=2 effective Lagrangian for three hierarchies of
supersymmetric particle masses, namely, when the gluino mass is comparable to,
much greater than, or much less than the masses of the first two generation
squarks. We find that the QCD corrections tighten the limits on squark mass
splittings by more than a factor of two.
