Heat treatment at relatively high temperatures (from 150 to 260 A degrees C) is an effective way to improve dimensional stability and bio durability. However, heat treatments usually reduce most of the mechanical properties of wood. This study was performed to investigate the effect of carbon fiber fabric on some mechanical and physical properties of LVL manufactured from heat-treated and untreated beech (Fagus orientalis Lipsky) wood. The laminated veneer lumber (LVL) and reinforced laminated veneer lumber (RLVL) samples were produced from heat-treated and untreated beech veneers in the five ply form (4 mm each) by using D-VTKA adhesive. Prior to the manufacture of LVL and RLVL, veneers were subjected to heat treatment at varying temperatures (160, 190 and 220 A degrees C) for 180 min. Carbon fiber revealed a clear effect on the mechanical (bending strength, modulus of elasticity in bending, compression strength) and physical properties (density, equilibrium moisture content, and volumetric swelling) of heat-treated and control LVL. The results showed that reinforcement with carbon fiber increased the density, the bending strength and modulus of elasticity in bending and the compression strength. Also, the volumetric swelling of reinforced laminated veneer lumber was more favorable than those of laminated veneer lumber.