We recommend magnetic resonance imaging of the sacroiliac joints as the first line imaging method in suspected inflammatory back disorder. Plain X-ray can be taken from those over 35 years of age. A nonconclusive finding in plain X-ray should be verified by MR imaging. For the present, diagnostic criteria for spondylarthritis do not take into account spinal changes. Typical spinal findings can, however, be helpful in making treatment decisions. In case the spinal region MR imaging should be utilized if possible, because radiography is particularly insensitive for thoracic spine. After a confirmed diagnosis, the inflammatory nature of the condition can usually be assessed clinically.