  Quark mass effects in ${\cal O}(\alpha_s^2)$ QCD corrections to the decay
rates of intermediate Higgs bosons are studied. The total hadronic rate and the
partial decay rate into bottom quarks are analyzed for the Standard (scalar)
Higgs boson as well as for pseudoscalar Higgs bosons. The calculations of three
different contributions are presented. First, the flavour singlet diagrams
containing two closed fermion loops are calculated for a nonvanishing bottom
mass in the heavy top limit. Their leading contribution, which is of the same
order as the quasi-massless nonsinglet corrections, and the subleading terms
are found. Large logarithms arise due to the separation of the pure gluon final
state from the bottom final states. Second, quadratic bottom mass corrections
originating from nonsinglet diagrams are presented.Third, nonsinglet
corrections induced by virtual heavy top quarks are calculated in leading and
subleading orders. It is demonstrated that, in order $\alpha_s^2$, the first
contribution numerically dominates over the second and the third ones.
