Special conditions such as water-logging may allow wood to survive thousands of years however some biological, chemical or physical modifications may occur. In this study, 300 year-waterlogged fir (Abies bornmulleriana M.) was tested for its chemical properties and natural decay and termite resistance in comparison with a recent fir. It was found that water-logging for 300 years caused few changes in chemical properties of waterlogged wood. Lignin was the most resistant component in the waterlogged wood specimens however polyoses and extractives were more affected during water-logging. Laboratory decay tests were performed using according to ASTM D 2017-81 standard method using two brown-rot fungi, Gloeophyllum trabeum and Serpula lacrymans and two white-rot fungi, Coriolus versicolor and Irpex lacteus. Wood specimens were also bioassayed against subterranean termite Coptotermes formosanus. Tests showed that 300 year water-logging had no any effect on natural durability however weight losses in the waterlogged specimens were slightly higher.