  We have carried out a first calculation of $J/\Psi$ production from nuclear
collisions within the covariant transport approach HSD, which has been very
successful in describing both hadronic and electromagnetic observables from
heavy-ion collisions at intermediate and high energies. The production of
$J/\Psi$'s is based on the Lund string fragmentation model, while its
interactions with hadrons are included by conventional cascade-type two-body
collisions. Adopting 6 mb for the $J/\Psi$-baryon cross sections and 3 mb for
the $J/\Psi$-meson cross sections above the $D\bar{D}$ threshold, we find that
data on $J/\Psi$ suppression from both proton-nucleus and nucleus-nucleus
collisions (including Pb + Pb) can be explained without assuming the formation
of a quark-gluon plasma in these collisions. Our microscopic studies thus
confirm the suggestion of Gavin et al. that $J/\Psi$ suppression observed in
nuclear collisions is largely due to absorption by comovers, i.e., the produced
mesons.
