Introduction: In the field of medicine, silver nanoparticles (Ag NPs) with their distinctive characteristics represent an interesting new cancer therapy. Cancer is a serious disease, despite the recent advances in its treatment; there are still some cases that are resistant to the current therapy.Aim of the work: This study aimed at examining the characteristics of 2 forms of silver nanomaterial (Ag NPs 1 and Ag NPs 2) and investigating their effect on breast cancer (MCF7) and liver cancer (HEP-G2) as well as on human normal melanocytes cell lines (HBF4).Materials and methods: It was found that both samples of nanoparticles have negative surface charge and their mean sizes were 9.02 nm and 24.6 nm respectively. Both Ag NPs 1 and Ag NPs 2 had a dose- dependent cytotoxicity on MCF7 and HEP-G2 with negligible effect on normal cell line (HBF4) measured by MTT assay.Results: Inhibitory Concentration 50 of Ag NPs1 and Ag NPs2 were 20.06 and 16.03 nmol/ml respectively. The resultant cell death was via apoptosis as illustrated by the inverted light microscopy. RT-PCR assessment revealed significant upregulation in Caspase 3 gene expression in the malignant cell lines exposed to each silver nanomaterials and remarkable downregulation VEGF and upregulation in TNF-α in either cancer cell line exposed to Ag NPs2 only. Meanwhile, the change in these cellular markers was minimal in normal human melanocyte cell line.Conclusion: This study indicates that silver nanoparticles can be used as anticancer agent with minimal effect on normal tissues. The cell viability depends not only on the size of Ag NPs but also their shape, surface charge and degree of repulsion between particles and aggregation.