The aim of this study was to determine the effect of abrasive treatment as a method of surface preparation on the strength of adhesive joints made of galvanised steel sheet. The subject of experimental investigations were adhesive joints of samples made of galvanised steel sheet DX51, 0.7 mm thick. The surfaces of the samples were abraded with coated abrasive tools of grain sizes P120, P180, P220, P400 and P600, and then degreased with PIKKO extraction solvent. The surface properties in terms of roughness and 3D surface topography were examined using a Hommel-Etamic T8000 RC120-400. The adhesive joints were made using Epidian 53 epoxy resin adhesive composition and IDA curing agent in a 100:40 weight ratio. Samples of single-lap adhesive joints were tested for strength on a Zwick/Roell Z150 testing machine, in accordance with the PN - EN 1465:2009 standard. The tests showed that the samples mechanically processed with an abrasive tool of P220 gradation show the best strength properties. Adhesive joints, in which the surface of the joined elements was mechanically processed with an abrasive tool of P120 gradation, obtained negative results. The obtained test results were subjected to further statistical analysis. The Shapiro-Wilk test was used to assess the normality of the distribution. Then, the non-parametric Kruskal-Wallis test and the median test were applied, which showed that there were no significant differences in the results obtained between the adhesive joints whose surfaces were prepared with P220 and P400 abrasive paper, i.e. both methods of surface preparation can be considered as the most favourable among those analysed during the adhesive bonding of DX51 galvanised sheets.