A new type of epoxy resin containing a 4,4＇-biphenylene moiety in the backbone (Bis-EBP) is synthesized and confirmed by elemental analysis, infrared spectroscopy, and H-1-nuclear magnetic resonance spectroscopy. In addition, to evaluate the influence of the 4,4＇-biphenylene group in the structure, an epoxy resin having a 1,4-phenylene group in place of the 4,4＇-biphenylene moiety (Bis-EP) is synthesized. The cured polymer obtained through the curing reaction between the new biphenyl-containing epoxy resin and phenol novolac is used for making a comparison of its thermal and physical properties with those obtained from Bis-EP and bisphenol-A (4,4＇-isopropylidenediphenyl)-type epoxy resin (Bis-EA). The cured polymer obtained from Bis-EBP shows markedly higher fracture toughness of 1.32 MPa m(1/2), higher glass transition temperature, lower moisture absorption, and higher thermal decomposition temperature.