  Incorporating its most relevant global symmetry, chiral effective models are
aimed at investigating, in a simplified framework, important aspects of the yet
unsolved QCD. We review some recent results obtained in these models on the
restoration of chiral and axial symmetries, on the boundary of the first order
phase transition region in the m_pi-m_K-plane at vanishing baryonic chemical
potential mu_B,and on the mu_B-T phase diagram.
