Beech is one of the major hardwood species in Europe. It is, however, highly susceptible to fungal attack both in the fresh state and during the storage. Understanding the alteration in chemical and mechanical properties of beech wood during the initial degradation state can lead to improved raw material utilization. Therefore, UV-microspectrophotometer (UMSP) and High-Performance Liquid Chromatography (HPLC) were employed to study the chemical changes in beech (Fagus Orientalis L.) samples infested naturally by white rot fungi. The mechanical properties of infested beech were also determined and compared with the sound wood. The UMSP showed an apparent degradation in the region of the S3 and the S2 layers. HPLC analysis illustrated that catechin was the main component both in sound and infested beech wood. Considerable reductions in the mechanical strengths, bending properties and compression strength, were also apparent due to infestation.