To determine whether needle-hook-wire anchoring strength is a factor in accidental repositioning of a hook wire, 5-cm Kopans and Hawkins II hook wires were placed axially (n = 9) and coronally (n = 5) in mastectomy specimens. The tension required to pull the hook wires 1, 2, 3, and 5 cm and to increase the barb angle to 90 degrees and 180 degrees were compared. The average anchoring strength of the Hawkins II hook wire was greater than that of the Kopans hook wire, by 2.6 times (P less than .001; all distances, both angles) with the wires in the axial plane and by 1.6 times (P less than .06; intervals and angles combined) in the coronal plane.