The three-loop QCD corrections to the $\rho$ parameter from top and
bottom quark loops are calculated.
The result differs from the one recently calculated
by Avdeev et al. As function of the pole mass the numerical value is given by
$\drho=\frac{3G_F M_t^2}{8\sqrt{2}\pi^2}(1- 2.8599\, \api
- 14.594\, (\api)^2 )$.