Reactive arthritis is an acute, sterile arthritis caused by infection, most commonly of the genitourinary system, respiratory tract or gastrointestinal tract. Most often it is the result of Chlamydia trachomatis, Yersinia, or Salmonella infections. Treatment depends on the disease form. In the acute form of infection, treatment is applied with antibiotics and no steroidal anti-inflammatory drugs. In the chronic form of disease, disease-modifying drugs (sulfasalazine or methotrexate) and corticosteroids should be used. In cases refractory to conventional therapy, one should consider the implementation of biological treatment (e.g., etanercept, or adalimumab) (Fig. 1–3, Table I).