Single wall carbon nanotubes (SWCNTs) were introduced in the interlaminar region of woven carbon fiberepoxy composites and the mode-I delamination behavior was investigated. Pristine (P-SWCNT) and functionalized (F-SWCNT) nanotubes were sprayed in the mid-plane of these laminates and delamination was initiated using a teflon pre-crack insert. The composite laminates were produced using vacuum-assisted resin transfer molding process. The interlaminar fracture toughness (ILFT) represented by mode-I critical strain energy release rate (GIc) for the initiation of delamination was measured using double cantilever beam tests. The specimens with pristine nanotubes and functionalized nanotubes showed a small effect on the ILFT. The specimens with P-SWCNTs showed stable crack growth and the potential for enhanced crack bridging along with slightly higher GIc than F-SWCNT specimens. Scanning electron microscopy images showed enhanced fibermatrix interfacial bonding in the specimens with F-SWCNTs. However, large unstable crack propagation was observed in these F-SWCNT specimens from loaddisplacement curves and crack propagation videos. This research helps in understanding the differences in mechanisms by addition of functionalized and unfunctionalized (pristine) nanotubes to the woven carbon fiberepoxy matrix composite laminates.