Toughening epoxy based composite materials using thermoplastic particles is a cost-effective approach to improve their poor delamination resistance. In this paper, the interlaminar toughening effect of different thermoplastic microparticles such as polyamide-6 and polyamide-12 particles for a carbon fibre/epoxy composite was investigated. The particles with a range of different areal weights were directly deposited on the prepreg surface to toughen the interlaminar region of the cured laminate samples. From the scanning electron microscope (SEM) observations, it was found that the effects of the three thermoplastic particles on the interlaminar fracture behaviour were different. It was also found that the particle areal weight affected the Mode-I fracture toughness differently depending on the particle material. In some cases, no toughening effect was observed.