TTP07-13 Dimensional reduction applied to QCD at three loops.

Recent developments in higher order calculations within the framework of Dimensional Reduction, the preferred regularization scheme for supersymmetric theories, are reported on. Special emphasis is put on the treatment of evanescent couplings, the equivalence to Dimensional Regularization, and the evaluation of $\alpha_s(M_{\rm GUT})$ from $\alpha_s(M_{\rm Z})$.