Abstract： Objective To study the immunophenotypic feature of CD+2 adult B cell acute lymphoblastic leukemia (CD+2 B-ALL) and provide evidences for the diagnosis, therapy and prognosis. Methods The immunophenotypes of 18 cases of adult CD+2 B-ALL and 68 cases of adult CD-2 B cell acute lymphoblastic leukemia(CD-2 B-ALL) were assayed by a panel of monoclonal antibodies (McAbs) with FACS. Results The age of CD+2 B-ALL adults was younger compared to that of CD-2 B-ALL. The patients in the CD; group were similar to CD-2 group for the expression of most of the cell surface antigens assayed. However, it was notable that expression frequencies of CD10 [(73.78±26.67) %] in CD+2 B-ALL was higher than those in CD; B-ALL [(52.84±35.25) %] (t = 2.35, P<0.05) and CD33 [(15.46±27.41) %] were significantly lower than that of CD2 BALL [(31.15+27.72) %] (t = 2.16, P<0.05). Both groups showed high positive expression for CD34 72.2 % (13/ 18) and 80.9 % (55/68), respectively (χ2 = 0.64, P >0.05). The CD20 expression in CD+2 B-ALL was lower than that in CD-2 B-ALL significantly (χ2 = 11.38, P <0.05). The myeloid antigen (CD13 or CD33) expression in CD+2 B-ALL 44.4 % (8/18) was lower than that in CD-2 B-ALL 72.1 %(49/68) (χ2 = 4.86, P <0.05). Conclusion Patients in the CD+2 B-ALL were similar to CD-2 B-ALL for expression of most of the cell surface antigens assayed. CD+2 B-ALL showed low expression frequency of myeloid antigens (CD13, CD33) and CD20 antigens than CD-2 B-ALL. These results suggested that those with the CD+2 B-ALL immunophenotype generally presented with favorable prognostic features and usually could achieve good outcomes after treatment.