Researchers used a high speed video camera to investigate the mechanism of end breakage due to weaver's and fisherman's knots in combed cotton yarns during 1 x 1 rib knitting. The results revealed that end breakage due to knitting. The results revealed that end breakage due to knots resulted from knots jamming at a cylinder needle hook because of an increase in yarn tension. Increases in the depth of the stitch draw, input tension, and knot takedown weight increased the rate of jammed knots and the end breakage rate for jammed knots. Fisherman's knots produced higher rates of jammed knots, more knots, and higher end breakage rates for jammed knots than weaver's knots under all knitting conditions. 5 refs.