Brain and acute leukemia, cytoplasmic (BAALC) is a novel molecular marker indicating an inferior outcome in acute myeloid leukemia (AML) with normal cytogenetics. The biological function of BAALC is largely unknown. In this study, BAALC gene expression in an acute myeloid leukemia cell line KG1a was knocked down by a small hairpin RNA (shRNA). The expression of BAALC mRNA and protein in the knockdown cells was significantly inhibited. The proliferation and apoptosis status in the knockdown cells were investigated. The growth curves and FACS analysis demonstrated that BAALC gene knockdown resulted in decreased proliferation and enhanced apoptosis in KG1a cells. These results indicated that BAALC may act as an adverse prognostic factor through prompting proliferation and inhibiting apoptosis in leukemia cells.