Plant extracts are a rich source of active chemicals; they have lately been employed in environmentally friendly nanoparticle synthesis. In one step of environmentally friendly synthesis, it is crucial that the biomolecules present in plant extracts can transform metal ions into small particles.    The study aimed to investigated the influence of silver nanoparticles (Ag NPs) synthesized from an aqueous extract of Cordia myxa and Ceratophyllum demersum on the osmotic fragility of human red blood cells (RBCs). Blood samples were treated with extracts of these two plants (0.125, 0.25 mg/ml, 0.357, and 0.75 mg/ml), and an osmotic fragility assay was done. The results showed a significant (p < 0.05) increase in RBC hemolysis in the presence of the extracts. Additionally, the results of the osmotic fragility assay revealed that the extracts of C. myxa and C. demersum have a hemolytic effect; these two plant extracts have similar effects on the fragility test of RBCs. In addition, the hemolytic impact of silver nanoparticles synthesized from C. myxa and C.  demersum extracts is lower than that of the original extracts. These effects of the extracts and Ag NPs from these two plant extracts are linked to several pharmacological characteristics of these extracts and the chemical constituents of the nanoparticles.