In the development of the continuum-based macroscopic theories for charged-hydrated soft tissues (Frank and Grodzinsky, 1987; Lai et al., 1991; Gu et al., 1993, 1998; Huyghe and Janssen, 1997), as well as in the classical physical chemistry theories for electrolyte solutions (Donnan, 1924; Katchalsky and Curran, 1975, Maroudas, 1979) it is assumed that electroneutrality is satisfied at every point in the continuum, i.e., there is no net charge at any point in the material. This assumption signifies that the electric displacement is divergence free, according to Maxwell’s macroscopic equations of classical electromagnetic theory. Some studies of electromagnetic interactions in biological tissues have suggested that, consequently, the electric field should also be divergence free for the electroneutrality condition to be strictly correct (e.g., Friedman, 1986; Hart, 1988). In this abstract we review basic concepts which establish that in general the electric field is not divergence free because of ionic polarization, and we derive a general expression for calculating the equivalent polarization charge using the triphasic theory of Lai et al. (1991).