The effect of frequency, temperature, and BaFe12O19 (BF) content on the dielectric constant $ \acute\varepsilon $, dielectric loss e?, and tan d were studied for barium ferritenatural rubber composites (RFC). The dielectric constant for barium ferrite was related to the preparation method, meanwhile the dielectric constant of natural rubber (NR) is relatively large compared to the theoretical value. The results showed that $ \acute\varepsilon $, e?, and tan d for RFC decrease as the frequency increases, however, at higher frequencies, the effect significantly weakens. At low ferrite loading, the dielectric properties are strongly influenced by BF content. Strong correlation between magnetic initial permeability and dielectric constant for hard magnetic material polymer composites was also observed. Increasing the content of barium ferrite in NR matrix enhances both e? and tan d. (c) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012