  Quark mass effects are included in the calculation of polarized structure
functions. In particular, the validity of fixed order perturbation theory and
of massless evolution is studied in the framework of heavy quarks structure
functions. The polarized version of the ACOT and MRRS interpolating schemes for
the evolution of massive quarks distributions is also developed and studied.
The different behaviours of the various approaches in $x$ and $Q^2$ are shown.
