In recent years using of silver nanoparticles due to its unique properties was increased. Medical plant, the Achillea biebersteinii is rich in anti-cancers compounds. The aim of this study was to investigate the cytotoxicity effects of AgNPs synthesized using Achillea biebersteinii extract on human ovarian cancer A2780 cells. Cytotoxic effects of AgNPs with MTT test was performed at 48 hours in concentration of 2, 4, 6, 8, 16 and 32 µg/ml. To study the cell death induced by AgNPs DAPI, acridine orange (AO)/ Propidium iodide (PI) staining and Annexin v/ Propidium iodide assay and activation of caspase 3 and 9 were assessed. Results: The results showed that the synthesized AgNPs decreased cell viability dose dependently, calculated inhibitory concentration of 50 % (IC50) was 4 µg/ml.  The results from AO / PI, DAPI staining, Annexin V / PI showed that in treated cells the percentage of apoptotic cells compared with control increased. In addition, the treated cells showed increased activation of caspase 3/9. Hence silver nanoparticles induced cell death through the caspase dependent pathway. The results suggest that AgNPs synthesized using Achillea biebersteinii   extract exert their cytotoxic effect by inducing apoptosis.