The effects of volume fraction and particle size of ferrite on the electric and magnetic properties of epoxy composites containing Ni-Zn ferrite were investigated. The composites were prepared by the cement mixed method and shaped as coaxial, toroidal and disc types. The complex permeability and permittivity were measured using an impedance-gain phase analyser (HP4194A) and a network analyser (HP8753C) in the frequency range 1 MHz-5 GHz. The complex permeability of the composites was found to increase as the ferrite content increased, and was characteristic of the frequency dispersion. A model to describe the frequency dispersion characteristics of the composite, which was a function of the ferrite content, is proposed here. The complex permittivity of the composite was found to be dependent mainly on the volume fraction of the ferrite and was relatively independent of frequency and particle size of the ferrite.