  An upper limit to the critical density for the transition to the deconfined
phase, at zero temperature, has been evaluated by analyzing the behavior of the
gluon condensate in nuclear matter. Due to the non linear baryon density
effects, the upper limit to the critical density, \rho_c turns out about nine
times the saturation density, rho_0 for the value of the gluon condensate in
vacuum <(\alpha_s/\pi) G^2>=0.012 GeV^4. For neutron matter \rho_c \simeq 8.5
\rho_0. The dependence of the critical density on the value of the gluon
condensate in vacuum is studied.
