In this note radiative corrections to the total hadronic decay rate of
the $\tau$-lepton are studied employing perturbative QCD and the
operator product expansion. We calculate quadratic quark mass
corrections to the decay rate ration $R_{\tau}$ to the order ${\cal
O}(\alpha_s^2 m^2)$ and find that they contribute appreciably to the
Cabbibo supressed decay modes of the $\tau$-lepton. We also discuss
corrections of mass dimension $D=4$, where we emphasize the need of a
suitable choice of the renormalization scale of the quark and gluon
condensates.
