The equation of state for nuclear matter at finite temperature and the properties of neutron stars are studied starting from an effective Lagrangian in the framework of the relativistic mean field theory. We find that the empirical properties of nuclear matter can be reproduced if the medium effects are mainly described in terms of the Brown-Rho mass scaling on top of the Bonn potential used as the underlying bare nucleon-nucleon interaction. In particular a correct symmetry energy at saturation density is obtained. The extrapolation of the equation of state to neutron matter and some predictions for the neutron-star masses are finally discussed and compared with other nucleonic many-body approaches.Physics, NuclearPhysics, Particles & ...