Two different dielectric models of biological cell suspensions have been used to describe the dielectric and conductive properties of the membrane of erythrocyte cells. The passive electrical properties of the cell membrane (the membrane permittivity ε′ and the membrane conductivity σ) have been evaluated on the basis of the Maxwell–Wagner–Hanai and Looyenga mixture equations and the results have been compared in order to discuss the validity of the two models employed. Based on a simultaneous fit of the permittivity ε′ and the electrical conductivity σ, the Looyenga equation furnishes a better description of the dielectric behavior of an erythrocyte cell suspension over an extended frequency range, in comparison to the Maxwell–Wagner–Hanai equation.