  We calculate the supersymmetric QCD corrections in order $\alpha_s$ to the
cross section $e^+ e^- \to \sq_i \bar\sq_j$ $(i,j = 1, 2)$ within the Minimal
Supersymmetric Standard Model. We pay particular attention to the case of the
left--right squark mixing and to the renormalization of the mixing angle. The
corrections due to gluino exchange turn out to be smaller than those due to
gluon exchange, but they can be significant at higher energies even for a
gluino mass of a few hundred GeV.
