Since ancient times the wood is one of the most important building materials. Because of climate change caused by man the wood is even more important as an ecologically very suitable material for living, and from the environmental point of view. We researched changes of some of the most important characteristics of oak wood. We used about 150 years old supporting part of the roof made from oak heartwood. Fungicidal properties were determined by subjecting the samples to 5 different fungi: Gloeophyllum trabeum, Antrodia vaillantii, Hypoksylon fragiforme, Pleurotus ostreatus andTrametes versicolor. Mechanical properties (bending strength, module of elasticity and compressive strength) were measured with a universal machine Zwick; the capillary uptake of water with tensiometer. We also made extraction by Soxhlet method. We used 3 different solvents: water, 70 % methanol and cycloheksane. Compared with the control oak wood, the old oak depends on the fungi the timber was exposed to. In the old oak wood, according to the control oak, the mass loss is almost 10 times larger after exposure to rusty gilled polypore (Gloephyllum trabeum). With the aging oak capillary uptake of water and mechanical properties suffer minimal or no change. Partial decline with age was observed in the proportion of extractives.