Abstract: The mechanical properties of the stitched laminates were compared with those of the unstitched laminates, considering changes in thickness due to stitching. Experimental investigation was conducted to understand the effect of stitching on tensile strength, compression strength, open-hole tensile strength, open-hole compression strength and failure mechanisms. The results show that the change in thickness due to stitching affects the volume fractions of in-plane fibers, which is important to assessing the mechanical properties of the stitched laminates.