&NA;Two cases of simultaneous Jefferson fracture of C1 and Type II odontoid fracture requiring surgical stabilization are reported. One patient required early stabilization because alignment could not be maintained in a halo vest, and the second patient required late stabilization for nonunion after a 3‐month period of immobilization in a two‐poster cervical brace. Although this uncommon injury can often be managed conservatively, surgical fusion will need to be considered in the setting of early or late instability. (Neurosurgery25:293‐297, 1989)