Spondyloarthritis (SpA) is an umbrella term for a group of rheumatic diseases characterised by inflammation of the sacroiliac (SI) joints and vertebral column; today, differentiation is made between axial SpA and peripheral SpA. Ankylosing spondylitis (Bechterew's disease) is the most typical form of axial SpA whereby sacroiliitis can be found on X-rays of the SI joints. Axial SpA can, however, also be present without radiographic evidence of sacroiliitis. A range of SpA-related symptoms can also manifest themselves outside the musculoskeletal system, for example, uveitis, psoriasis and inflammatory intestinal diseases. Tumour necrosis factor (TNF)-α inhibitors play an important role in the treatment of SpA. New classification criteria have recently been established in which MRI of the SI joints and the presence of the HLA-B27 tissue antigen are key. Axial and peripheral SpA should be recognized early in order to be able to successfully treat these conditions.