Shear strengths of small clear-wood specimens from Chinese Fir and Seguin chestnut were tested according to Chinese ISO 3347 and American ASTM 143 standards.The objective was to examine the effect of sample thickness and cutting angle on the shear strengths.Analysis of variance showed that there was no significant difference in the shear strength between the different sample thicknesses for both species.However,the result of t-test indicated that the cutting angle had considerable effect on the shear strength.The results provide references for revising the existing standard method of testing shear strength parallel to the grain for wood.