  We calculate the two--loop electroweak corrections to the fermionic decay
width of the Higgs boson at leading order in $m_{H}$. The sum of one--loop and
two--loop radiative corrections turns out to be at 6% level over the whole
range of $m_{H}$ where the perturbation theory is supposed to be a sensible
approximation. We show that the perturbative approach breaks down at $m_{H}
\sim$ 1.4 TeV, and address the question of its relevance beyond this limit.
