The effective medium approximation (EMA) has been applied for the prediction of the permeability of packed beds filled with polydisperse spheres. The EMA assumes a model system in which a packing particle is surrounded by a fluid envelope and an effective medium beyond the envelope. This model provides an analytical expression for the permeability of the packed bed as a function of the packing size distribution and the porosity. Unlike the present model, most existing models utilize an average packing size for the permeability prediction as they are not capable of fully incorporating the packing size distribution. The permeability prediction of the present model has been compared with those of recent numerical calculations, the semiempirical Kozeny-Carman correlation, and experimental data that are available. The Kozeny-Carman correlation, which is widely accepted in industrial applications, uses a mean particle size to account for the packing size distribution. Both the present model and the Kozeny-Carman correlation show a good agreement with the numerical results for packed beds of monodisperse particles and experimental data for packed beds of bidisperse particles. While the prediction of the present model agrees well with the Kozeny-Carman correlation when the packing size distribution is narrow, a significant deviation is noted as the size distribution becomes broader.