Two sets of criteria have been proposed and widely accepted in the last few years for the classification of the whole spectrum of spondyloarthropathy, including the undifferentiated forms. These classification criteria--the Amor criteria and the European Spondyloarthropathy Study Group criteria--are not, however, particularly helpful for diagnosis because they do not include the milder and monosymptomatic forms. Outcomes research in spondyloarthritis is growing, and new instruments have been suggested. An international study group of experts is working to propose a core set of measures to be included in future clinical trials on ankylosing spondylitis. Intrasynovial corticosteroid injections in the sacroiliac joints may represent a valid alternative for patients with inflammatory low back pain that is unresponsive to nonsteroidal anti-inflammatory drugs. Sulfasalazine is an effective therapy for the psoriatic arthritis and peripheral arthritis of ankylosing spondylitis. A recent study has suggested its efficacy in reactive arthritis as well. In reactive arthritis, the use of long-term antibiotic therapy has been proposed and is under study.