This manuscript investigated the effect of waste tar from particle board factories on some physical and biological resistance properties of Scots pine (Pinus sylvestris L.) and beech (Fagus orientalis L.) woods. Solutions were prepared by dissolving waste tar in ethanol:toluene (1v:1v) in concentrations of 5%, 10%, 15% and 20% and treated under vacuum and pressure. In addition, surface coating (SC) was applied by spreading 96% waste tar on the wood surfaces after treatment. Deep-treated and surface-coated (DT+SC) wood samples were exposed to the wood-decay fungi (Corillous versicolor L. and Neolentinus lepideus Fr.) and wood destroying house borer (Hylotrupes bajulus L.) larvaes. Total phenolic content, water uptake, water-repellent efficiency and surface contact angle were tested. The highest mean weight loss (45.23%) was found in the beech wood control samples exposed to C. versicolor. Beech samples deep-treated with a 20% concentration and surface treatment (DT+SC) yielded a mass loss of 14.03%. The H. bajulus larvae mortality rate was found to be 80% in the Scots pine wood samples deep-treated with 20% waste tar. The deep treatment with the waste tar solution significantly increased the surface contact angle values of the Scots pine wood, thereby significantly reducing the wettability of the wood compared to the untreated control samples.