In this study the effect of interleaved nanofiber on mode I and mode II fracture response of composite laminates is considered. For this aim, electrospun Nylon 6,6 and poly-caprolactone (PCL) nanofibers and their combination are put in the mid-plane of unidirectional glass/epoxy laminates, which are then subjected to double cantilever beam (DCB) and end notched flexure (ENF) fracture tests. Results showed that PCL nanofibers could improve modes I and II energy release rate (G(I) and G(II)) almost equally with 25% and 24% increase. Influence of Nylon 6,6 nanofiber is mostly on mode II loading with 68% enhancement, while its effect on mode I is negligible (4.5% increase). It is also shown that combination of these two kinds of nanofibers lead to 21% and 56% increase in G(I) and G(II), respectively which are between the results of the individual nanofibers. (C) 2013 Elsevier Ltd. All rights reserved.