  We compute the QCD running coupling on the lattice as defined from the
3-gluon vertex. We present the results of an exploratory study at $\beta=6.0$
on a $16^4$ lattice, which show that for momenta larger than 2 \Gev, the
coupling runs according to the 2-loop asymptotic formula, allowing a precise
determination of the $\Lambda$ parameter. Our renormalization procedure
corresponds to a momentum subtraction scheme in the continuum and, most
remarkably, one does not need lattice perturbation theory to match the results
to MSbar scheme. We obtain $\alpha^{\MSB}(M_Z) = 0.115 \pm 0.003 \pm 0.008$.
