Structural adhesives are progressively replacing conventional bonding methods, being constantly adopted for new applications. The most commonly used structural adhesives are epoxies due to their good mechanical, thermal and chemical properties, having a wide range of application. Epoxies are recognized for their high stiffness and strength, induced by their high degree of crosslinking. While the densely cross-linked molecular structure is responsible for the excellent properties of these materials, it also makes them inherently brittle, resulting in low ductility and toughness. Several researchers have, in the past decades, found necessary to mitigate this effect and developed new methods to increase the toughness of structural adhesives. There are many processes depicted in the literature on how to increase the toughness of adhesives. For example, the inclusion of particles (of nano or micro scale) is a successful technique to improve the toughness of structural adhesives. In this chapter, natural micro particles of cork are used with the objective of increasing the toughness of a brittle epoxy adhesive. The fundamental basis of this concept is for the cork particles to act like crack stoppers, leading to more energy absorption. An overview of how the micro cork particles can be used as reinforcement material for brittle resins is described. The main parameters that affect the mechanical properties of composite resin/cork, kinetic and chemical reactions between resin and cork and how this new material behaves in hygrothermal degradation, were analysed. It is concluded that the cork can be used as reinforcing material, promoting increased toughness of the adhesive without any chemical changes in the molecular structure or premature degradation of the adhesive.