In addition to the typical clinical symptoms, conventional x-rays and magnetic resonance imaging (MRI) are important for the diagnosis and management of ankylosing spondylitis (AS). While radiography is mainly useful for detecting chronic structural changes, MRI is, in addition, able to detect active inflammation. The detection of structural changes in the sacroiliac joints and, in part, the spine, remains the gold standard for the diagnosis of AS. The detection of active sacroiliitis or spondylitis in early disease stages is only possible using MR techniques such as STIR and T1 post-gadolinium sequences. Lateral radiographs of the spine are useful for detecting shiny corners and the characteristic syndesmophytes and ankylosis. The modified Stoke Anklyosing Spondylitis Spine Score (SASSS) is the best scoring method for quantifying such changes, allthough only the cervical and the lumber spine are evaluated with this method. MRI changes can also be quantified. New scoring methods are sensitive to change only 3 months after initiation of therapy with anti-TNF agents.