The records and roentgenographs of 113 rheumatoid patients treated by total hip or knee arthroplasty were analyzed retrospectively. The cervical spine roentgenographs were evaluated for significant atlantoaxial subluxation, atlantoaxial impaction, and subaxial subluxation. One or more of these findings were present in 69 (61%) of the patients. Thirty-five of the 69 (50%) with roentgenographically documented cervical spine instability had no signs or symptoms of instability at the time of admission for joint replacement. This high incidence of cervical spine instability in a select population of rheumatoid patients emphasizes the importance of preoperative evaluation of the cervical spine including flexion and extension lateral roentgenographs.