We present a mean field theory of phase diagram of solutions of flexible polyelectrolytes with neutralizing counterions. We show that the temperature-concentration curve, corresponding to the coexistence of polymer-rich and polymer-poor solutions, is highly asymmetric, and the degree of polymerization of the polymer has only a weak effect. We have addressed the role of added salt in destabilizing the homogeneous phase of polyelectrolyte solutions, within the framework of quasi-two-component description of the multicomponent system.