Polymers, such as Polyvinylidene Fluoride (PVDF) and its copolymers with Trifluoroethylene (TrFE), are both dielectric and ferroelectric materials. They exhibit polarization hysteresis loop when subjected to cycled electric field. To be pyroelectric, these materials have to be poled. Poling or fatiguing these materials influences not only the ferroelectric properties, but also the dielectric properties. For both thick and sub-micron films. The dielectric properties were characterized by the measurement of the dielectric permittivities and loss as function of frequency at differents temperatures. Based on the experimental results, it is found that poling or fatiguing the polymers substantially increases the crystallinity and the size of crystallites. However, the effect of fatigue on the dielectric properties is only evident at low frequencies.