Cure monitoring of thermosetting resin matrix composites during the molding process of polymer matrix composites is important for the quality control and reliable manufacturing of composite products. Since dielectrometry can in situ measure the cure status during the actual curing process of polymer matrix composites, it is being widely employed as cure monitoring apparatus. Although dielectrometry is more convenient in measuring the cure status of resin than differential scanning calorimetry (DSC), the former requires complicated calculation to yield the cure information from the dissipation factor of the resin because the measured dissipation factor of the resin by dielectrometry contains viscosity information rather than the degree of cure of the resin. In this paper, the dissipation factor of glass fiber-epoxy composite was measured using developed dielectrometry sensors and an electrical circuit. Then the isothermal degree of cure was calculated and compared with that obtained from DSC experiments. (C) 2001 Elsevier Science B.V. All rights reserved.