a shafkhan@ust.hk, b ikxaa@ust .hk, c arshee@comsats.net.pk, d mejkkim@ust.hk , SUMMARY This work investigates the influence of nanoclay on the fracture resistance and mechanical properties of nanocomposites and the corresponding carbon fiber-epoxy hybrid composites. The nanoclay augmented the impact and static fracture toughness, as well as the mechanical properties, such as flexural strength and modulus. The fracture surfaces were examined to identify the pertinent toughening mechanisms involved.