  We discuss the use of fermion polarization for studying neutral Higgs bosons
at a photon collider. To this aim we construct polarization asymmetries which
can isolate the contribution of a Higgs boson $\phi$ in $\gamma\gamma\to f \bar
f$, $f=\tau/t$, from that of the QED continuum. This can help in getting
information on the $\gamma\gamma\phi$ coupling in case $\phi$ is a CP
eigenstate. We also construct CP-violating asymmetries which can probe CP
mixing in case $\phi$ has indeterminate CP. Furthermore, we take the MSSM with
CP violation as an example to demonstrate the potential of these asymmetries in
a numerical analysis. We find that these asymmetries are sensitive to the
presence of a Higgs boson as well as its CP properties over a wide range of
MSSM parameters. In particular, the method suggested can cover the region where
a light Higgs boson may have been missed by LEP due to CP violation in the
Higgs sector, and may be missed as well at the LHC.
