We report the effects of surface damage and crystal orientations on fracture strength of single crystal silicon. Tensile tests of nine types of specimens from (110) SOI wafer, i.e. specimens of three crystal orientations with three different surface morphologies prepared by the specimen patterning process, showed that surface morphology improvement doubled average tensile strength: e.g. 110 strength varied from 1.8 GPa to 3.6 GPa, while average tensile strength difference among crystal orientations was less than 20 % on each fabrication conditions. Using SEM observation, we found tensile fracture characteristics of three crystal orientations: in 100 specimens the fracture origin location changed by the fabrication conditions, while 110 and 111 specimens respectively showed quantitative relationships between surface morphology and tensile strength common to different fabrication conditions. © 2013 IEEE.