Researchers have found that the mechanical properties of the polymer composites may be enhanced by the modification of the matrix by the addition of nanoparticles. While most of the previous literatures are limited only to two-phase systems, the outcome of this work has introduced a three-phase composite developed with nano-materials as additional reinforcements. As most of the composites are neither homogeneous nor isotropic, it is highly important to understand the influence of nano-modification of the matrix on the mechanical properties of unidirectional (UD) fibre reinforced composites. In this work, diglycidyl ether of bisphenol A (DGEBA)/triethylene tetramine (TETA) system is nano-modified by the addition of alumina and zirconia nanoparticles. The unidirectional glass fibres are used along with the unmodified and modified epoxy resins for fabricating composite laminates by vacuum bagging process. The interlaminar shear tests were performed over the specimens machined from various laminates prepared out of neat and nano-modified samples. The interlaminar shear strength (ILSS) of the composite is investigated at different angles (longitudinal, transverse and 45°) of the fibres. Though the ILSS of the fabricated composites is greater along the longitudinal direction, the enhancements in the ILSS by the addition of nano-fillers were higher along transverse direction. This is because of the dominant properties of matrix at transverse direction. Any changes in the properties of the matrix influence a lot on ILSS of the composite along the transverse direction. Further, due to the larger specific surface area (SSA) of the alumina nanoparticles, the ILSS of the composite containing alumina nano-fillers is found to be superior to the composites filled with zirconia nanoparticles at similar particle size and loading.