Rhus coriaria, popularly known as sumac, has been used as a spice powder in the Middle East for centuries. It contains a broad range of naturally occurring compounds such as flavonoids, proteins, anthocyanins and volatile oils. It showed a putative importance in treatment of different disorders including cancers. In the current study, R. coriaria fruit extract was used for green synthesis of silver nanostructures (Ag-NSs) and their anticancer activity was tested against human breast cancer cells (MCF-7). The aqueous fruit extract was prepared. The synthesis of Ag-NSs under different conditions was optimized. The optimal reaction medium comprised 1:2 concentration of fruit extract and 3 mM concentration of silver nitrate solution. The green-synthesized Ag-NSs were confirmed by using UV-Visible spectroscopy at a range 300-700 nm, transmission electron microscopy (TEM), X-ray diffraction (XRD) and zeta potential measurements. The anti-proliferative activity of Ag-NSs was confirmed with inhibitory activity on MCF-7 cell line growth. The results showed that the IC50 values at 24 and 48h were 14.27 and 13.4 μg/ml, respectively. In conclusion the results of this study provide a simple, rapid, non-toxic and eco-friendly protocol for green-synthesis of Ag-NSs, which could be used as an alternative and interesting approach for safe and simple synthesis of Ag nanoparticles for biomedical uses.