CD20 expression is associated with early recurrence and inferior survival in precursor-B acute lymphoblastic leukemia patients treated with chemotherapy. Whether CD20 influences outcomes after allogeneic hematopoietic stem cell transplantation (allo-HSCT) is unknown. We analyzed CD20 expression on blasts at diagnosis in 157 patients who underwent allo-HSCT in the first complete remission (57%) or the second complete remission (43%). Of 125 evaluable patients, 71 were ≥ 20 years of age. CD20 expression was observed in 58 patients (46%; 52% of children, 39% of adults). There was no association between age, Ph(+) status, white blood cell count at diagnosis, and CD20 positivity. After allo-HSCT, disease-free survival at 5 years was 48% for all patients, 55% (95% confidence interval 40%-67%) for CD20(+) patients, and 43% (95% confidence interval 30%-54%) for CD20(-) patients (P = .15). Relapse did not differ between the groups. These results can serve as a reference to evaluate incorporation of anti-CD20 therapeutics to HSCT for the CD20(+) acute lymphoblastic leukemia subset. Clinical trial numbers for www.clinicaltrials.gov are NCT00365287, NCT00305682, and NCT00303719.