In order to improve the adhesion property between ultra high molecular weight polyethylene (UHMWPE) fiber and epoxy matrix, our research has been focused on modification of the matrix with reactive graphitic nanofibers (r-GNFs). Upon previously developed nano-epoxy with r-GNFs, the adhesion property was characterized by fiber bundle pull-out tests in this study. Fiber bundle pull-out tests were performed on both single-end and double-end specimens. Comparison of the adhesion properties of single-end and double- end specimens was made to reveal the effectiveness of pull-out test method using single-end specimens. The results indicate that nano-epoxy can improve the interfacial property between UHMWPE fiber and nano-matrix effectively. It is found that, for 0.3 wt% r-GNFs nanomatrix compared to pure epoxy bundle specimens, there are about 34% and 27% increase of critical load (initial debonding load) and peak load, respectively, and about 116% and 107% increase of critical debonding energy and pull-out energy, respectively. (c) 2006 Elsevier Ltd. All rights reserved.