Carbon aerogels have excellent potential to act as reinforcements for improving the material properties of polymer-based composites because of their porous nanostructures and large surface areas. However, the addition of carbon aerogels to polymer-based composites has effects on the material properties of the final composites, and those effects are not clear. In this study, an epoxy matrix was modified with carbon aerogel, and this modified matrix was then used to manufacture carbon fiber-reinforced polymer (CFRP) laminates. The effects of the addition of the carbon aerogel to the laminates on the mechanical properties and delamination resistance were investigated. The modulus and strength of the laminates were slightly increased by the addition of the aerogel to the composite laminates. The addition of the aerogel to the laminates led to an appreciable improvement in the interfacial property and adhesion between the fibers and matrix, and consequently, the delamination fracture energy was increased. The Mode I delamination fracture energy was measured to be 265 J m(-2) for the laminate with the unmodified matrix, whereas that of the laminate with 0.1 wt% aerogel was 346 J m(-2). The delamination fracture energy caused by Mode II loading was increased from 655 J m(-2) for the unmodified laminate to 1088 J m(-2) for laminate modified with 0.5 wt% aerogel. Fractographic observation showed significant differences in the fracture surface morphology between aerogel-modified and unmodified CFRP laminate.