To observe the expressions of CD10 in childhood B-acute lymphoblastic leukemia (B-ALL) and to define the role of CD10 in minimal residual disease (MRD) detection. 58 cases of childhood B-ALL were studied in this program. Four-color flow cytometry was used to analyze the characteristics of B-ALL phenotypes. The four-color fluorochrome labeled antibody combinations of CD10 with other markers were used to detect MRD. The results showed that CD10 overexpression (CD10(bright)) was detected in 65.5% (38/58) of B-ALL patients and a strong correlation between CD10(bright) and CD34 expression was also observed, i.e. CD10(bright) expression most frequently happened in B-ALL with high percentage of CD34 positive cells. In detection of MRD, CD10(bright), combined with other markers, could effectively distinguish normal cells with leukemic cells, even if there was no any other marker that can be used. It is concluded that CD10(bright) expression correlates with high expression of CD34 in B-ALL, it is a good marker for MRD detection. The combination of CD10 and other markers can be applied in B-ALL MRD detection with flow cytometry.