A study was conducted to determine the effects of wood pretreatment on the bonding strength of wood materials. The woods used for the test samples (based on BS EN 204) were oriental beech (Fagus orientalis Lipsky), Scotch pine (Pinus sylvestris L.), oak Quercus petreae Liebl.), and chestnut (Castanea sativa Mill.). They were impregnated with Tanalith-C, creosote, and Protim 230 WR-paraffin by full-cell methods according to ASTM D 1413-76 standards and the directions of the manufacturers. After (impregnation, shear strength tests (based on BS EN 205) were applied on the samples bonded with poly(vinyl acetate) (PVAc), Desmodur-VTKA, and Pattex fast. The highest shear strength was obtained in nonimpregnated (control) and PVAc-D-1 glued oak (5.328 N/mm(2)), and the lowest shear strength was obtained in Protim 230 WR-paraffin and Pattex fast glued chestnut (0.169 N/mm(2)). Accordingly, the impregnation process negatively affected the adhesive bonding strength. Impregnation chemicals, especially containing oily or similar substances, could not be proposed for wood elements exposed to shear strength. (c) 2006 Wiley Periodicals, Inc.