The effect of material type, fabric structure, stitch, and cycle number of tensile fatigue has been studied on dynamic fatigue behavior of interlock weft knitted fabrics in course direction. To investigate the effect of controllable factors on fatigue value, Taguchi method has been used. The fatigue value has been defined as the percentage of variation in bagging resistance of knitted fabrics before and after tensile fatigue cyclic loading. A signal to noise ratio analysis has been adopted to identify the most effective parameters on fatigue value and also to determine the best factor levels for producing knitted fabrics with lowest value of fatigue. According to the SN ratio analysis, fabric structure shows the dominant effect on fatigue value followed by stitch density, number of cyclic loads and blend ratios.