Current treatment regimens for hangman's fracture, or traumatic spondylolisthesis of the axis, emphasize rigid immobilization using a halo orthosis. A retrospective study was undertaken to assess the safety and efficacy of nonrigid immobilization in the treatment of these fractures. Records of 64 patients with hangman's fracture treated over a 19-year period (1975-1994) at one institution were reviewed. Thirty-nine of these patients presented with a displacement of C-2 onto C-3 measuring less than 6 mm and no contiguous cervical fractures. All these patients were treated with nonrigid immobilization, consisting primarily of a Philadelphia hard collar worn for 10 to 14 weeks; all showed stable fracture healing on follow-up flexion-extension radiographs. None of the patients experienced neurological sequelae or significant disability at follow-up review. The results of this series indicate that the majority of patients with hangman's fractures, including all patients with displacement measuring less than 6 mm and no contiguous fractures, may be treated successfully with nonrigid immobilization. This management regimen avoids the increased morbidity and cost associated with rigid immobilization using a halo orthosis.