Abstract: The utility of an expansion fastener including an externally threaded shaft having a head shaped so as to be capable of being engaged by a manipulative tool, a generally cylindrical longitudinally split sleeve located around the shaft, a nut threaded on the shaft, the sleeve and the nut including coacting surfaces capable of expanding the sleeve as the nut is moved on the shaft can be improved by utilizing coacting structures on the end of the sleeve remote from the head and on the nut for preventing relative rotation between the sleeve and the nut as the shaft is turned. Preferably the sleeve is twisted slightly in a spiral-like manner so that an end of the sleeve serves as one of the coacting structures which engages an adjacent ridged or other not smooth surface of the nut serving as the other coacting structure.