Testing the MSSM with the Mass of the W Boson

We review the currently most accurate evaluation of the W boson mass, M_W, in the Minimal Supersymmetric Standard Model (MSSM). It consists of a full one-loop calculation, including the complex phase dependence, all available MSSM two-loop corrections as well as the full Standard Model result. We analyse the impact of the phases in the scalar quark sector on M_W and compare the prediction for M_W based on all known higher-order contributions with the experimental results.