Chlamydia-induced arthritis (CIA) is an inflammatory reactive arthritis caused by extraarticular infection with Chlamydia trachomatis. CIA presents as peripheral arthritis or spondylarthropathy. Extraarticular manifestations are present in most but not all cases, Reiter's syndrome occurs only in a minority of patients. Detection of Chlamydia trachomatis in genitourinary smears and demonstration of serum-antibodies against chlamydial antigens lead to diagnosis. Analysis of synovial fluid reveals nonpurulent inflammatory synovitis and, in some cases, chlamydial antigen has been demonstrated in synovial specimens. The therapy of CIA combines physical medicine, NSAID and shortterm antibiotic treatment of the genitourinary infection. Whether longterm antibiotic therapy or-in chronic cases--DMARDs are successful, needs further investigation.