Immune Thrombocytopenia (ITP) is an autoimmune disease in which there is thrombocytopenia due in part to destruction of platelets by autoantibodies. In adults, the disease is most often chronic and in the most severe forms, the treatment of choice is splenectomy. Rituximab was suggested during chronic ITP when used with 4 weekly infusions of 375 mg/m2, 60% of patients achieve an immediate response and 30 to 40% a prolonged response. These encouraging results and the apparent good tolerance advocate for using rituximab as first-line treatment for patients refractory to splenectomy. In France, Afssaps - French Health Products Safety Agency has recently issued a temporary protocol processing to authorize rituximab in this indication. Nevertheless, many questions remain unresolved, including the tolerance of long-term treatment and the risk of late relapse in responders. This justifies the creation of this register, whose establishment is recommended by Afssaps - French Health Products Safety Agency.