We study the spin properties of top quarks produced in collisions of polarized photons in the threshold region. For a relatively heavy top quark the influence of non-perturbative effects is small and its polarization parameters can be predicted in perturbative QCD. The measurements of the top polarization may allow a novel test of QCD in the\(t\bar t\) system. In particular, they may provide a new way to determine the precise value of αs and to study the properties of the top quark.