An experimental study was conducted to study the improvement of damage resistance in laminated composites with the addition of electrospun nano-interlayers as the interleave material. The electrospinning process was utilized to fabricate nanofibers and nanofibril mats with and without the CNTs by using three thermoplastic polymers: polycarbonate, poly(phenylene oxide) and polystyrene. The optimal mixture ratio of the solvent and concentration of the CNTs was found to yield optimal fiber formation. It was observed that the fiber becomes thicker with the increase of polymer concentration and the CNT contents. Mechanical tests under Uniaxial tensile loading were carried out with a delamination-prone layup of [30/-30/90/90/-30/30](T) by placing the polycarbonate electrospun nanofibril mats at the interface between each ply. The difference in total thickness of the laminates with and without five nano-interlayers was less than 0.001 mm, which is negligibly thin. The stress levels at the first microcracking damage, delamination damage and ultimate load-drop increased by 8.4%, 8.1% and 9.8%, respectively, with the addition of the nano-interlayers as compared with the pristine specimens. The number of rnicrocracks decreased significantly with the addition of the nano-interlayers. The increase of the FPF strength with the nano-interlayers was analyzed with the Weibull statistical theory and the prediction agreed well with the experimental data. (c) 2007 Elsevier Ltd. All rights reserved.