We are beginning to understand the clinical nature of JAS, its relationship with other SSA, and factors involved in its pathogenesis. Clinical data may now allow early recognition of JAS through the identification of children with the SEA syndrome or chronic arthritis associated with the HLA-B27. Comparative clinical studies of the prevalence of the disease and the role of immunogenetic, racial and environmental factors are needed. It may be necessary to review current criteria for the diagnosis of JRA and to develop similar criteria for the diagnosis of AS in childhood and adolescence.