This study analyzed the effect of small interfering RNA specific for the Bcl-2 gene (siRNA Bcl-2) on the proliferation and chemotherapeutic sensitivity of pediatric A-BLL cells. Marrow samples were obtained from sixty newly-diagnosed A-BLL pediatric patients. The Bcl-2 mRNA expression in these samples was quantified by real time polymerase chain reaction. The Bcl-2 mRNA re-expression was analyzed by RNA interference using Bcl-2-siRNA. Cellular proliferation was detected using the MTT (Thiazolyl Blue Tetrazolium Bromide) assay. The cell apoptosis was quantified by flow cytometry. The Bcl-2 mRNA expression was significantly higher in the drug-resistance group than in the chemotherapy sensitivity group prior to chemotherapy.