The progress of immunopathology allowed the development of targeted drugs or biotherapies. Among them, monoclonal antibodies against T or B lymphocytes or against a cytokine are reported. Monoclonal anti-TNF antibodies are a major therapeutic advance because they can stop the clinical, biological and radiographic evolution of rheumatoid arthritis (RA). Monoclonal anti-CD20 lymphocytes give promising results; they are able to induce prolonged remissions. Monoclonal anti-IL6 receptors are currently being evaluated. They are efficacious in adult RA and in Still's disease. Because of the infectious risk linked to these drugs, the ratio benefit/risk must be carefully evaluated before the prescription of a biotherapy.