Forty-one patients who had rheumatoid arthritis were treated with a cervical arthrodesis and were followed for a minimum of twenty-three months. Twenty patients had had an isolated atlanto-axial subluxation; five, isolated cranial settling; and four, subaxial subluxation alone. Twenty patients had an atlanto-axial arthrodesis; sixteen, an occipitocervical arthrodesis; and five, a posterior arthrodesis of the subaxial spine. In addition, two patients had a transoral odontoidectomy and one, an anterior cervical vertebrectomy. At the latest follow-up, thirty-six (88 per cent) of the patients had osseous union, two had fibrous union but were stable, and three had a non-union. All of the problems with union occurred in the patients who had had an isolated atlanto-axial arthrodesis. Clinically, twenty-seven (66 per cent) of the patients had improved, fourteen were unchanged, and none were worse. The preoperative neurological status remained the same postoperatively in thirty patients (73 per cent) and it improved in eleven (27 per cent). Twenty-one of the twenty-three patients who had had marked pain preoperatively had little or no pain at the latest follow-up. Complications included a transient hemiparesis in one patient, a superficial wound infection in two, displacement of an anterior graft in one, a broken wire in three, and erosion of methylmethacrylate into the outer part of the occipital cortex in one. Four patients died, but not as a result of the operation.(ABSTRACT TRUNCATED AT 250 WORDS)