It has been our experience in twenty-one cases, and hence it is our belief, that the comparatively simple and conservative operation to remove the bony obstruction to motion against the rim of the acetabulum is efficacious in the treatment of slipped epiphysis with severe displacement. Restoration of good motion and function, correction of deformity, and relief from pain is accomplished without the necessity of cervical osteotomy or wedge resection and with little residual limp. This procedure has an important place in the treatment of selected patients with severe slipping of the upper femoral epiphysis.