This study presents the feasibility of the vacuum assisted resin infusion (VARI) process for strengthening and repair of glass/ vinyl ester composites. The process has attracted considerable interest in the marine ector as a route to the manufacture of new structures such as boat hulls but has not been discussed as a route to repair damaged parts where adhesion is required between a repair preform and the original material. In this work, the adhesion that may be obtained between an infusion resin and a composite substrate is interpreted using a fracture mechanics approach involving double cantilever beam (DCB) Mode-I fracture toughness tests. It is shown that once adequate adhesion is established from a comparison of particular pretreatments, both Mode-I critical strain energy release rate values and crack resistance curves are increased by the introduction of ultra-thin polyester veils to toughen the impregnation resin at the critical bonding area of the repair configuration. Post-failure examination of the fracture surfaces show that the failure locus is transferred from the interface to the reinforced resin bondline. This exploits the high strain-to-failure characteristics of the thermoplastic veil materials. The strong crack resistance observed is attributed to the ply bridging mechanism of the thermoplastic fibres that deform plastically in the wake of the crack. Two different data reduction methods are adopted for the current study, namely the compliance calibration (CC) and the modified beam theory (MBT) and a relationship is derived from the variation of their parameters n and Delta in order to analyse and compare the fracture energy values obtained.