Polylactide-polyglycolide (PLGA) has been one of the most important biodegradable and biocompatible materials. In this study, nanofibrous membranes of PLGA were fabricated using an electro fiber spinning setup that consisted of a syringe and needle (the internal diameter is 0.42 mm), a ground electrode, an aluminum sheet, and a high voltage supply. The dielectric properties of the electrospun membranes were characterized. The experimental results suggested that the electrospun membranes exhibited ultralow dielectric behavior. The influences of the nanofibers diameter and the density of the membranes on the dielectric properties were also instigated. It was found that the dielectric constants decreased with the fiber diameter and increased with the density of the nanofibrous membranes. By employing the electrospinning process, one will be able to fabricate polymeric membranes with ultralow dielectric performance. (C) 2011 The Japan Society of Applied Physics