Abstract: An assembly for preventing rotation of a fastener nut comprises a retaining block having at least one aperture therein, the aperture having a longitudinal axis and including nut retaining device therein for preventing rotation of the nut in the aperture. The assembly further includes a retaining member adapted to releasably engage the retaining block for preventing axial movement of the nut in a direction generally parallel with the longitudinal axis of the aperture. In one embodiment, the retaining member is a generally U-shaped member having a pair of legs including a tab on each of the legs for releasably engaging a pair of slots formed on opposing faces of the retaining block. In a second embodiment the retaining block includes a pair of tabs projecting from opposing faces thereof.