THE TYPE II odontoid fracture, initially described by Anderson and D'Alonzo, is the most common axis fracture. Several factors that predict the need for operative intervention have been discussed in the literature; however, the initial treatment remains somewhat controversial. We present the case of a 20-year-old woman who suffered a Type II odontoid fracture during a skiing accident. She was managed initially with halo-vest immobilization, and after 12 weeks, bony fusion was documented by plain spine radiographs and tomography. Routine follow-up cervical spine films at 8 months after her injury revealed no union at the previous fracture site and resultant atlantoaxial instability. A posterior C1-C2 fusion was therefore performed, leading to a long-term solid bony fusion. There are no previous reports in the literature describing a nonunion after radiographically documented healing of a Type II odontoid fracture. We present this case in order to emphasize the importance of scheduled follow-up examinations, including cervical spine films, for at least 12 months after a documented fusion. Further reports of similar cases may generate a more thorough understanding of the pathogenesis of delayed nonunion and may elicit factors that will predict its development.