Wood is a natural polymer, easily workable, affordable and environmentally friendly material. Because of anisotropic structure, mechanical properties are directed. In this thesis, the influence of orientation structure was studied on bending strength and bending modulus of elasticity on subfossil elm wood. Subfossil wood is preserved trunk that is hundreds of years have been in the water streams, in very specific condition. Elm is very rarely found as subfossil wood, because of the Dutch disease has almost disappeared from the natural forests of Southeast Europe. The test samples were cut from about 670 years old trunk extracted from the river Sava, between Grebnice and Domaljevac in Bosanska posavina. The microscopic analysis of three typical sections (cross, radial and tangential) hasshown that trunk is a tree of the genus Ulmus (elm). Bending strength and bending modulus of elasticity were determined by the three point bending test. Three different series of samples - LT, L45 ° and LR were examined. Direction of flexural force was vertical to the fibers in all tested samples, and the direction of force is changed in relation to the course of the growth rings: 0 ° (LT), 45 ° (L45 °) and 90 ° (LT). For both tested properties the values are the largest in the series L45 °. The values in the LT series are slightly higher than the values of the LR series. The results were statistically analyzed by Weibull distribution. The coefficient of determination of Weibull function is very high (close to 1) for all series and for both properties. It was found that the value of bending strength and bending modulus of elasticity of the subfossil elm wood are not lower in order to the recent elm, despite the 700-years staying in very specific conditions.