  We present a measurement of the cross section for $Z$ production times the
branching fraction to $\tau$ leptons, $\sigma \cdot$Br$(Z\to \tau^+ \tau^-)$,
in $p \bar p$ collisions at $\sqrt{s}=$1.96 TeV in the channel in which one
$\tau$ decays into $\mu \nu_{\mu} \nu_{\tau}$, and the other into $\rm
{hadrons} + \nu_{\tau}$ or $e \nu_e \nu_{\tau}$.
  The data sample corresponds to an integrated luminosity of 226 pb$^{-1}$
collected with the D{\O}detector at the Fermilab Tevatron collider. The final
sample contains 2008 candidate events with an estimated background of 55%.
  From this we obtain $\sigma \cdot$Br$(Z \to \tau^+ \tau^-)=237 \pm
15$(stat)$\pm 18$(sys)$ \pm 15$(lum) pb, in agreement with the standard model
prediction.
