In this study, it was aimed to determine the efficiency of bio-oils on wood-water relations, decay and insect resistance. Bio-oil was obtained by pyrolysis of Scots pine wood (Pinus sylvestris L.) using extruder type pyrolyzer at 450,550 and 600 degrees C. Scots pine sapwood was impregnated with different bio-oils and water absorption, fungicidal characteristic and resistance against Hylotrupes bajulus was investigated. FTIR spectral analysis showed that the main constituents of bio-oils are various phenolic compounds. High leachability of the bio-oils was also found by UV-Vis spectral analysis and is a drawback when the oils are used as wood protecting agents. The results indicated that the wood impregnated with these bio-oils showed lower water absorption than that of the control group. The hydrophobic characteristics of wood samples treated with full and empty cell process did not differ significantly although the oil uptake of samples treated with full cell process was significantly higher than that of the empty cell process. Decay test results against brown rot fungi (P. placenta) indicated that the samples impregnated with bio-oils had a mass loss of 7-10%, which is lower than the mass loss of the untreated wood samples. Samples treated with bio-oils showed resistance against Hylotrupes bajulus according to EN 47 standard, except samples treated with the light part of bio-oil obtained at 600 degrees C.