This thesis deals with the issue of strength of sewn stitches of selected upholstery fabrics and its changes imposed by specific factors. Modeling factors are the thickness of the connecting thread and the stitch length.The paper is divided into IX. chapters. The introductory parts of the thesis cover the literature review of issue covering upholstery fabrics and connecting materials. There are also stated standardized procedures for determining the strength of areal and linear fabrics and the procedure for determining the strength of sewn stitches according to the methodology STRIP. In the experimental part there are characterized specific covering upholstery materials and selected modeling factors of sewn stitches. The chapter Result of experiments states the results of exams determining strength of the sewn stitches and evaluate an impact of selected factors of sewn stitch on its strength for a set of covering upholstery materials.