The authors studied the incidence of atlanto-axial joint involvement by conventional radiography and CT in 183 patients with classical or definite rheumatoid arthritis (RA). In determining lesions the significance of factors such as age, sex, duration and severity of the disease was evaluated. Atlanto-axial subluxations turned out to be quite frequent (30%) in the series of patients examined and were directly correlated with age, duration and stage of the disease, and extraarticular manifestations. Clinical symptoms were evident in only 70.9% of cases, confirming the correlation reported by other authors between clinical manifestations and radiologically observed lesions. Traditional radiography performed in the dynamic position revealed a prevalence of anterior subluxation, whereas CT gave a precise indication of the entity and type of atlanto-axial lesion. In conclusion, the authors confirm the importance of such investigations in all patients with RA, even those without evident clinical manifestations. They also emphasize the necessity of periodic monitoring in view of the possible risk of mortality in these patients.