More than 90% of ALL with a B phenotype (2/3 of cases in adults)express the surface antigen CD22 on leukemic blasts which thus represents an interesting target for therapy. Epratuzumab is a humanized anti-CD22 antibody produced by Immunomedics, Inc, Morris Plain (New Jersey, USA). Epratuzumab has already shown efficacy in lymphoma patients. Only one study, including 15 children, has been published so far reporting the efficacy and the toxicity of Epratuzumab in the setting of ALL in monotherapy, one can observe 8 stable disease, 3 progressions and 4 partial responses. When combining chemotherapy and Epratuzumab, 9CR were observed with acceptable toxicity. Tolerance was acceptable.