This article presents the study of dielectric properties of synthetic and natural fiber reinforced epoxy composites. Bamboo and glass fibers were both chopped and woven. These fibers were then used for reinforcing epoxy, with different fiber loadings. The dielectric properties of these composites were studied with reference to their fiber loadings, frequencies, and chemical treatment of the natural fibers at room temperature. It was found that dielectric properties increased with the increase in the concentration of fibers filled in the epoxy matrix, for the entire frequency range. This was due to the increase in the orientation and interfacial polarization. The treated fiber composites had lower dielectric properties due to decreased hydrophilicity of the natural fiber. The chopped glass fibers reinforced epoxy composites have the highest dielectric constant, among all tested composites. J. VINYL ADDIT. TECHNOL., 24:E201–E216, 2018. © 2018 Society of Plastics Engineers