When injection molding complex parts, often knit‐lines are formed during the mold filling stage. These knit‐lines are well‐known as particularly critical regions in the mold when mechanically loaded. Using three test materials, polystyrene (PS), polycarbonate (PC) and polyoxymethylene (POM), the relationship between a design and a processing parameter and the effects of the knit‐lines on the tensile properties of injection molded plates with holes is quantified by the variation of a socalled knit‐line‐factor ak1. Finally, for PS a comparison of the influence of knit‐line‐formation by a splitted melt stream and by multi‐gating on the mechanical level is given.