The present monograph emphasizes the influence of twist factor, rotor speed and opening roll speed on characteristics of cotton rotor- spun yarns. Furthermore, the effect of scouring with caustic soda and enzyme on the characteristics of cotton rotor- spun yarns has been evaluated and compared with equivalent ring- spun yarns. The yarns made from the same fibre stock on the two different spinning systems were reeled into skeins (caustic and enzyme treated under standard conditions). For both yarn structures the tensile strength is reduced on scouring, however, the strength loss is more in caustic scoured yarns. It has been observed that regardless of processing parameters used, the scoured yarns have lesser flexural rigidity and hairiness than grey yarns. The unevenness and imperfections of both ring and rotor yarns increased considerably after scouring treatments. The overall changes in the properties of the caustic and enzymatic scoured yarns suggest that potential of both techniques can be properly utilized by evaluating their respective advantages and disadvantages. This study provides a set of experimental results, discussion and comparison between the two processes.