The properties of wool fibers treated with chlorine (Basolan® 88 and Kroy-resin) were compared with surface modification observed by scanning electron microscopy (SEM), frictional properties and mechanical properties. The changes in surface morphology, frictional and physical properties of the single wool fibers are presented. Coating resin on the chlorinated wool fibers results in a significant reduction in the fiber coefficient of friction, as the resin smoothes the protruding edges of the fiber scales. However it increases the directional friction effect (DFE) of the fibers. It is postulated that the DFE may limit the ability of those surface fibers to form fuzz and hairiness of spun yarn could reach the critical height required for pill formation. Meanwhile, the fiber tensile strength may be attributed to pills pulling-off during pills formation, indicating a slowing rate of fuzz formation and consequently pill formation.