  We calculate, to 3 loops in perturbation theory, the bare $\beta$-function of
QCD, formulated on the lattice with the clover fermionic action. The dependence
of our result on the number of colors $N$, the number of fermionic flavors
$N_f$, as well as the clover parameter $c_{SW}$, is shown explicitly.
  A direct outcome of our calculation is the two-loop relation between the bare
coupling constant $g_0$ and the one renormalized in the MS-bar scheme.
  Further, we can immediately derive the three-loop correction to the relation
between the lattice $\Lambda$-parameter and $g_0$, which is important in checks
of asymptotic scaling. For typical values of $c_{SW}$, this correction is found
to be very pronounced.
