  In this work radiative corrections in the total hadronic decay rate of the
tau-lepton and some moments of its differential distributions are studied
employing perturbative QCD and the operator product expansion. We calculate
quadratic quark mass corrections in the strange mass to the decay rate ratio
R_tau to the order O(\alpha_s^3 m^2) and find that they contribute appreciably
to the Cabibbo suppressed decay modes of the tau-lepton. Using the results of a
recent experimental analysis, we obtain m_s(1 GeV) = 200 \pm 40_exp \pm 30_th
MeV.
