Data that are relevant to the general understanding of the juvenile-onset spondyloarthropathies are reviewed here. Seronegative enthesopathy and arthropathy syndrome is considered the earliest recognizable form of juvenile-onset spondyloarthropathy, from which other syndromes and diseases emerge. The group also includes juvenile-onset ankylosing spondylitis, a disease defined in adult-based terms when definite changes have occurred in the axial joints; ankylosing tarsitis, a complex disorder in which foot problems resemble those of the spine in ankylosing spondylitis; Crohn's disease and ulcerative colitis-related peripheral and, especially, HLA-B27 axial disease; reactive arthritis and Reiter's syndrome, which might be further classified according to its cause; and juvenile psoriatic arthritis, a disease that resembles juvenile rheumatoid arthritis more than does juvenile-onset spondyloarthropathy.