The inflammation seen in spondyloarthropathy has very distinctive features; it is preferentially located at the sites of attachment of muscle or ligament to bone, where ectopic ossification occurs; it particularly affects men, and usually starts after growth has ended; phagocytes clearly predominate over lymphocytes at sites of inflammation; microorganisms come into play when there is a favorable genetic predisposition; and, lastly, the inflammation of spondyloarthropathy is highly sensitive to non-steroidal anti-inflammatory agents. A better comprehension of the mechanisms of inflammation would help in understanding the pathogenesis of spondyloarthropathy.