Dielectric constant (epsilon'), loss factor (tan delta) and molecular dynamic behavior of liquid crystalline epoxy cured with diamine were studied by thermally stimulated discharge current (TSC) technique and were compared with the conventional epoxy system. The relaxation timer and the activation energy of reorientation of the dipoles for each TSC characteristic band were expressed as Arrhenius relationship. Liquid crystalline epoxy (LCE) monomer was diglycidyl ether of biphenyl (DGEBP) and the conventional epoxy was diglycidyl ether of bisphenol A (DGEBA). The conventional epoxy had two sub-Tg relaxations; gamma-relaxation was related to the motion of glycidyl ether segment and beta-relaxation was due to the crankshaft motion of the hydroxylether group. LCE thermoset exhibited another gamma'-relaxation in addition to those two relaxations; the reorientation of mesogenic unit. The para-ether linkage of the biphenyl mesogenic unit allows it to rotate without disturbing neighborhood unit. (C) 2002 Elsevier Science B.V. All rights reserved.