Abstract : Fiber-reinforced laminated composites have excellent mechanical properties along the fiber in-plane direction. However, they do not have very good properties in the transverse direction. The objective of this research is to deal with this problem by using graphene oxide (GO), plasma-treated multiwall carbon nanotubes, and nanodiamond extra pure powder with epoxy-terminated butadiene nitrile liquid rubber to improve the through-thickness fracture toughness of glass/epoxy unidirectional pre-preg laminates. The experimental results show that by adding carbon nanoparticles with rubber in small quantities, the mode-I interlaminar critical energy release rate can be improved by 50 to 103 %. Furthermore, it was observed that there was an increase in flexural stiffness by 15 % with the addition of nanodiamond extra pure powder to rubber. However, when GO was used, the mode-I interlaminar fracture toughness improvement was reduced as compared to other nanoparticles modified by glass/epoxy fiber laminates. The fracture surfaces were analyzed using scanning electron microscopy to understand the increase in toughness in modified glass epoxy pre-peg laminate system. © 2017 by ASTM International.