  We discuss the supersymmetric O(alpha_s) QCD corrections to e+ e- -> squark_i
+ antisquark_j (i,j = 1,2) and to squark_i -> q' + chargino_j, q + neutralino_k
(i,j = 1,2; k = 1...4) within the Minimal Supersymmetric Standard Model. In
particular we consider the squarks of the third generation stop_i and sbottom_i
including the left-right mixing. In the on-shell scheme also the mixing angle
has to be renormalized. We use dimensional reduction (which preserves
supersymmetry) and compare it with the conventional dimensional regularization.
A detailed numerical analysis is also presented.
