Abstract： Objective To explore the clinical significance of expression of the CD20 in 96 adults B-lineage acute lyrnphoblastic leukemia (B-ALL). Methods The CD20 expression of 96 acute lymphoblastic leukemia patients were determined by flow cytometry. The characteristics ,examination results and outcome were analyzed retrospectively. Results Out of the 96 patients, there were 29 (30.20 %) patients with CD20positive and 67 (69.79 %) patients with CD20 negative. The distribution of age, infiltration of liver, spleen, and lymphnodes, the expression of myeloid lineage marker, the incidence of Ph chromosome and bcr-abl fusion gene and the complete remission rate within 4 weeks between CD20 positive and negative groups showed no significant differences (P ＞ 0.05). The relapse rate and 3 year over survival rate of adults B-ALL in CD20 positive and negative groups were 54.55 % and 14.80 %, 29.63 % and 37.30 % respectively with a significant differences (x2 = 0.42, 5.31, P＜ 0.05). Conclusion The expression of CD20 in adult B-ALL appears to be not associated with clinical features and CD20 expression in adult B-ALL cells appears to be associated with poor prognosis.