We recently discovered that minute additions of sodium chloride (NaCl) during the preparation of electrospun polymethyl methacrylate (ES PMMA) nanofibers significantly raise their mechanical properties. In the present work, twisted yarns made of such ES PMMA nanofibers were prepared and the effects of NaCl mediation and yarn structure and twist on the resulting mechanical properties were studied. Improvements in these properties due to NaCl mediation are again observed for yarns, as they were for single ES fibers. Furthermore, both Young's modulus and the ultimate strength of the yarns show an increase with increasing angle of twist up to a maximum, followed by a decrease at higher twist angles. (C) 2012 Elsevier Ltd. All rights reserved.