Rheological characterization of polymers above their melting points is performed with dielectric spectroscopy. A new in-line interdigitated dielectric sensor as well as a commercial off-line sensor were used to make the measurements. The dielectric dissipation or loss factor of a molten polymer was found to be directly proportional to independently measured rheological properties of the polymer. Time-temperature superposition was used to translate dielectric and rheological curves to master curves where the curves are comparable in form, but the activation energy of a dielectrically-induced relaxation was found to be lower than a rheological translational motion. The more localized and homogeneous effects imparted to the polymer during the dielectric measurement may cause the polymer to undergo a viscoelastic transition at a lower energy than the flow-induced transition in rheological measurements. The dielectric methods detailed herein provide a new noninvasive technique to measure the viscoelastic properties of molten polymers.