Abstract:The m W − m Z interdependence in the Standard Model is studied in the M S scheme at the two-loop level, including the known higher-order contributions. The relevant radiative parameters, ∆α(µ), ∆r W ,ρ are computed at O(α 2 ) taking into account higherorder QCD corrections and the resummation of the reducible contributions. We obtain m W = 80.357 ± 0.009 ± 0.003 GeV where the errors refer to the parametric and theoretical uncertainties, respectively. A comparison with the known result in the On-Shell scheme gives a difference of ≈ 6 MeV. As a byproduct of our calculation we also obtain the M S electromagnetic coupling and the weak mixing angle at the top mass scale,α(M t ) = (127.73) −1 ± 0.0000003 and sin 2θ W (M t ) = 0.23462 ± 0.00012.