The present study was aimed to investigate the effect of telomerase activity in berbamine-induced apoptosis and the regulation of B cell leukemia/lymphoma 2 ( bcl-2) gene expression in human leukemia HL-60 cells. Apoptosis of HL-60 cells was induced by berbamine (10 microM) for 3, 6, 12 and 24 h. Apoptosis and bcl-2 were determined by flow cytometry analysis. A polymerase chain reaction-based telomeric repeat amplification protocol assay was used to detect the telomerase activity. Berbamine induced growth arrest and apoptotic cell death in HL-60 cells. The telomerase activity was inhibited in a time-dependent manner during the berbamine-induced apoptosis of HL-60 cells, and the expression of bcl-2 was progressively down-regulated by berbamine. Inhibition of the telomerase activity of HL-60 cells was closely related to the berbamine-induced apoptosis. The present results indicate that inhibition of telomerase and reduced bcl-2 gene expression may play a role in the berbamine-induced apoptosis of HL-60 cells.