Sweet chestnut wood is considered as one of the most durable Slovenian domestic wood species. There are several reports that the most important factor influencing wood durability are extractives. To find out if sweet chestnut wood durability is based on extractives and their contents, specimens were extracted and exposed to 5 different fungal species: Gloeophyllum trabeum, Antrodia vaillantii, Pleurotus ostreatus, Trametes versicolor and Stereum hirsutum. A part of specimens was extracted with soxhlet extraction with 3 different solvents. Fungal decay was determined gravimetrically after 12 weeks of exposure. In parallel, Norway spruce and beech wood samples were exposed to the wood decay fungi as well. Our results indicate that influence of extractives on wood durability is important although natural durability of sweet chestnut heartwood specimens after extraction is not significantly lowered. It can be resolved that natural durability of non-extracted sweet chestnut heartwood can be classified as very durable against fungal decay (mass loss lower than 1 %).