In this study, the aimisto experimentally determine the effects of different sewing threads and different washing types on fabric tensile and sewing strength properties. In this context, two types of denim fabrics (one produced with elastane and the other without elastane) were selected as samples. Then, experimental samples were sewed with three different sewing threads (polyester/ polyester core-spun, polyester/ cotton core-spun and polyester filament) at the same thread number, and three different washing processes (rinse, enzyme, and stone with enzyme) were applied. Afterwards, fabric tensile and seam strength tests were performed by following the related standards. Finally, the test results were analyzed using a statisticalsoftware package programme (SPSS 20.0). It was seen that, in general the relationship between the washing type and fabric tensile strength was statistically significant. In addition, the highest sewing strength valueswere obtained before washing, and the lowest values were seen after stone washing with enzyme. The sewing thread giving the highest warp sewing strength values in all washing types was the polyester filament.