OBJECTIVE To compare the chronic changes between the sacroiliac joints (SIJ) and the spine or the hip joints in conventional radiography of patients with ankylosing spondylitis (AS) and discuss the clinical staging of this disease. METHODS All images of the joints of the AS patients were evaluated twice in blinded manner by two doctors. The cervical spine, lumbar spine, sacroiliac joints and hip joints were separately evaluated by BASRI, and the results were averaged and analyzed. Definite involvement was defined as a score > or=2. RESULTS Thirty-seven AS patients (81.0% male with mean age of 28.49 years) were examined, and 81.0% of them had definite involvement of the spine and 40.5% of hip involvement. Pearson product-moment correlation coefficient was 0.459 between BASRI-SIJ and BASRI-s, and 0.465 between BASRI-SIJ and BASRI-h. CONCLUSIONS Separately, the severity of SIJ changes can not represent the severity of changes in the spine and hip, etc, therefore SIJ changes may not be sufficient evidence for AS staging.