Hem-fir plywood were exposed to two brown rot fungi,Gloeophyllum trabeum andPostia placenta, and one white rot fungus,Trametes versicolor, to investigate the effect of fungal decay on mechanical properties of plywood. Results showed that modulus of rupture (MOR) and modulus of elasticity (MOE) of hem-fir plywood declined significantly by inoculating fungi, and weight loss of sample had a modest decrease. The fungi also made a greater effect on MOR than on MOE. Of three fungi,Postia placenta caused a most significant weight loss, andGloeophyllum trabeum resulted in a largest flexural properties loss. Substantial declines in MOR and MOE of hem-fir plywood were also observed when the plywood samples were stored under wet conditions over 15 weeks, even in, the absence of fungal attack.