Abstract: Objective: To evaluate the cytotoxicities of inhibitors of TopoⅡincluding adriamycinand pirarubicin to low differentiated squamouse nasopharyngeal carcinoma (NPC) cell line SUNE-1 andthe apoptotic effect inducing and the expression of Livin when treated with these drugs.Methods: Thecytotoxicities of adriamycin and pirarubicin to SUNE-1 were detected by MTT assay. The cell-apopto-sis rate was analyzed by Annenxin V FITC staining and detected using flow cytometry. The changes ofmitochondrial transmembrane potential and expression of Livin were detected using flow cytometry.Results: The proliferation of SUNE-1 could be inhibited by adriamycin and pirarubicin. The effectswere dose-dependent. The IC 50 of adriamycin and pirarubicin to SUNE-1 was 0.0041±0.0003 μg/mland 0.0038±0.0008μg/ml, respectively (P=0.542). The apoptosis rate and negative mitochondrial trans-membrane potential increased with the treatment time. SUNE-1 presented change of Livin expressionwhen treated with ADM or THP, but the increased level of Livin expression induced by THP was lowerthan those induced by ADM.Conclusions: Adriamycin and pirarubicin can inhibit the proliferation andinduce apoptosis of SUNE-1 in vitro. They can upregulate expression of Livin in NPC cells. But there is a relatively lower level in expression of Livin when treated with pirarubicin than treated with adri-amycin. This suggests that pirarubincin maybe more effective to treat NPC patients than adriamycinwhich need further confirmation in clinical practice.