A connector backshell assembly is provided for strain relief mounting to an electrical cable. The assembly includes a backshell having forward and rearward ends and an axially extending cable-receiving aperture therethrough. A toroidally configured, radially compressible strain relief coil spring surrounds the cable and is disposed near the rearward end of the backshell. A compression nut is engageable with the backshell for selective rotational and axial movement relative thereto. The compression nut includes a forwardly facing concave cam surface for engaging and radially compressing the coil spring into strain relief engagement with the cable. An interference surface is operatively associated with the backshell and non-rotatably engageable with the strain relief coil spring to prevent rotation of the coil spring with the compression nut relative to the backshell.