Nanodielectric composites have been developed in recent years attempting to improve the dielectric properties such as dielectric properties such as dielectric constant, dielectric strength and voltage endurance. Conventional dielectric material development followed the paths of organic polymers, inorganic ceramics and thin films separately, due to type of capacitors, manufactured, polymeric film and multilayer ceramic capacitors, polymer dielectrics show very high dielectric strength (> 300 kv/mm), lover dielectric losses (< 0.01) and adequate mechanical flexibility in processing, which is important in thin film capacitors. However they have low relative dielectric permittivity or constant (< 4) and low operating temperature (< 200oC) compared to ceramic materials. Ceramic dielectrics tend to have very high dielectric permittivity (> 100) but relative low dielectric strength (< 50 kv/mm) or may be piezoelectric associated with the structure of ceramic. Nanodielectric composites belong to a new type of materials, engineered for improved specific functionality such as better performance in electrical insulation. In the present study, BaCO3 as a filler has been dispersed in polycarbonate in various concentration, Dielectric constant and loss has been measured as a function of frequency.