During manufacturing or service conditions, adhesively bonded composites are often subjected to impact. This impact may result in a reduction in strength and structural integrity of engineering components that are composed of adhesively bonded composite structures. The investigation of the degradation of strength of structural joints is, therefore, of paramount importance for their successful performance. Impact resistance of bondline in adhesively joined composites can be altered by the addition of nanoclay in the adhesive during fabrication of adhesive joints. In this study, impact test was carried out on graphite-epoxy composite panels bonded with nanoclay adhesive at different impact energies using drop-weight impact test equipment. Adhesive joints were fabricated by adding nanoclay in volume fractions of 1, 2 and 5% in the adhesive bondline. For comparison, plain adhesive joints were fabricated without nanoclay incorporation in the bondline. Impact testing was performed on these joints at 5, 10 and 20 J, to study the effect of inclusion of nanoclay in the epoxy adhesive. In order to determine the flexural load bearing capacity and stiffness reduction after impact, a three-point bending test was conducted on unimpacted and impacted specimens. The results showed that there was an improvement in impact capacity, however there was a reduction in flexural strength due to nanoclay incorporation. (C) Koninklijke Brill NV, Leiden, 2010