The electroosmotic flow of a general electrolyte solution through a fibrous medium is modeled theoretically taking the effect of double-layer polarization into account. The result obtained is applicable to an arbitrary level of electrical potential. We show that if the effect of double-layer polarization is neglected using the linearized Poisson-Boltzmann equation will underestimate electroosmotic velocity. The deviation becomes inappreciable, however, if kappa a is either very large or very small, kappa and a being, respectively, the reciprocal Debye length and the radius of a fiber. If the surface potential is high, the variation of electroosmotic velocity as a function of kappa a may exhibit a local maximum and a local minimum, and the larger the porosity of the fibrous medium the lower the level of surface potential for the local extremals to occur. If kappa a is small, the effect of surface potential on the electroosmotic velocity is more significant than that of double-layer polarization, and the reverse is true if kappa a is large,