  In this paper we investigate the role of the high density effects in the
heavy quark production cross section in $pA$ processes at RHIC and LHC. We use,
as initial condition, a gluon distribution consistent with fixed target nuclear
data and the Glauber-Mueller approach to describe the high density effects. We
show that this process can be used as a probe of the presence of the high
density effects. Moreover, we include these effects in the calculation of the
heavy quark production in $AA$ collisions, verifying that they cannot be
disregarded both in the estimates of quarkonium suppression and in the initial
conditions of the quark-gluon plasma.
