During the past year, no big advances were reported in understanding the pathogenesis or treatment of reactive arthritis (ReA). The need for generally accepted diagnostic criteria has become a central issue. Regarding pathogenesis, attention has been drawn to a similarity between ReA and the experimental antigen-induced arthritis. Molecular mechanisms of the HLA-B27-associated pathogenesis have remained, in spite of intensive research, so far a mystery. It is apparent that antibiotics have no effect on the fully developed reactive arthritis, with the exception of patients with Chlamydia-triggered ReA, who might benefit from a course of antibiotics.