On the scheme dependence of the Electroweak radiative corrections

We study the scheme dependence of the two-loop expression for the $\rho$-parameter of the Standard Model in the heavy $t$-quark mass limit $m_{t} \gg m_{w}$\mathrm{.}Inthe$\ms$-schemethetwo-loopelectroweakcorrectiontothe${\cal O}(m_{t}^{2})$termin$\dr$isfoundgreaterthantheQCD$\as$-correction.