Clothing macnufacturing is the last link in a long and complicated process by which two dimensional fabrics are transformed into three-dimensional garments by sewing the fabric pieces together. However, whatever the quality of the fabric is, if the sewing operation is not performed appropriately, the resultant garment will be of inferior quality. The fabrics produced today have apparently changed a great deal when compared with those produced 25 or 30 years ago. The qualities now demanded in modern fabrics are that they be elegant in appearance, soft and supple in handle and possess special draping qualities. For this reason, the degree of slip or distortion by the slippage of weft yarns over warp yarns, or vice versa, is of paramount importance. Slippage at seams of garments, etc. depends on several factors such as the structure of the fabric, the type of the seam and the condition of stitching. The purpose of this article is to explain the effects of stitch density, sewing machine speed and sewing thread properties on seam slippage.