Currently, nanotechnology and nanoparticles (NPs) are recognised due to their extensive applications in medicine and the treatment of certain diseases, including cancer. Silver NPs (AgNPs) synthesised by environmentally friendly method exhibit a high medical potential. This study was conducted to determine the cytotoxic and apoptotic effects of AgNPs synthesised from sumac (Anacardiaceae family) fruit aqueous extract (AgSu/NPs) on human breast cancer cells (MCF-7). The anti-proliferative effect of AgSu/NPs was determined by MTT assay. The apoptotic properties of AgSu/NPs were assessed by morphological analysis and acridine orange/propidium iodide (AO/PI) and DAPI staining. The mechanism of apoptosis induction in treated cells was investigated using molecular analysis. Overall results of morphological examination and cytotoxic assay revealed that AgSu/NPs exert a concentration-dependent inhibitory effect on the viability of MCF-7 cells (IC50 of ∼10 µmol/48 h). AO/PI staining confirmed the occurrence of apoptosis in cells treated with AgSu/NPs. In addition, molecular analysis demonstrated that the apoptosis in MCF-7 cells exposed to AgSu/NPs was induced via up-regulation of Bax and down-regulation of Bcl-2. These findings suggested the potential use of AgSu/NP as cytotoxic and pro-apoptotic efficacy and its possible application in modern medicine for treating certain disorders, such as cancer.