The fracture toughness of a liquid crystalline epoxy was compared with that of a standard bisphenol-A based epoxy to understand how both the liquid crystalline structure and the crosslink density affect fracture toughness. For the liquid crystalline epoxy. the liquid crystalline domain size decreased with increasing temperature of cure and away from the stoichiometric formulation. Quantitative fractography showed that there is a competition between the liquid crystalline domain structure and the stoichiometry in determining the fracture toughness. At some cure conditions the effect of the domains is dominant. When the cure conditions are adjusted to reduce the domain size, the domains become too small to affect the fracture toughness, and thus the effect of the stoichiometry is dominant. The result is that the formation of liquid crystalline structure only increases the fracture toughness relative to that of a traditional epoxy at and near the stoichiometric formulation.