The term 'spondyloarthritis', which is preferred to 'spondyloarthropathy', refers to a group of similar diseases with distinct clinical features and a common genetic predisposition, rather than one disease with different clinical presentations. Mainly for clinical purposes, five disease subtypes are recognized: ankylosing spondylitis (AS), psoriatic spondyloarthritis, reactive spondyloarthritis, spondyloarthritis associated with inflammatory bowel disease, and undifferentiated spondyloarthritis. Irrespective of the disease subtype, the main clinical manifestations of spondyloarthritides are inflammatory back pain, peripheral arthritis, enthesitis and anterior uveitis, while other organ manifestations are rare. The need for a standardized, evidence-based approach to disease classification led to the development of the European Spondyloarthropathy Study Group preliminary criteria for spondyloarthritis in 1991, which confirmed the unifying concept of this group of diseases. In the past 10 years, the work of the European Spondyloarthropathy Study Group has been taken over by the Assessments in AS working group. There is still a considerable delay in diagnosis of AS and, because of the well-documented efficacy of anti-tumor-necrosis-factor therapy for all spondyloarthritis subtypes, diagnostic criteria (especially for early forms of spondyloarthritis) are needed. Diagnosis can be achieved by determination of the predominant clinical manifestation, and by the inclusion of sensitive diagnostic tools for early disease (such as HLA-B27 genotype and MRI) in the criteria set. In addition, because of the high incidence of back pain in affected individuals, the development of practical screening parameters that facilitate referral to the rheumatologist is important.