After rheumatoid arthritis, ankylosing spondylitis (AS) is one of the most common rheumatic diseases. AS belongs to the spondyloarthritis group which is characterised by inflammation of the spine and has a strong genetic association with the HLA-B27 antigen. Recently, the Assessment of SpondyloArthritis International Society has introduced new international classification criteria for spondyloarthritis, i.e. axial and peripheral manifestations AS is one of the known axial spondyloarthritides but it is also a type of axial spondyloarthritis that does not show radiographic abnormalities, but has the same symptoms and risk factors that characterise axial spondylarthritis. This form is known as non-radiographic axial spondylarthritis. Peripheral spondyloarthritis is characterised by peripheral arthritis, enthesitis and dactylitis. Examples of peripheral spondyloarthritides are psoriatic arthritis and reactive arthritis, previously known as Reiter's syndrome.