Silver nanoparticles (AgNPs) that were biologically synthesized using Moringa oleifera leave extract showed good antibacterial activity against two tested bacterial strains namely: Pseudomonas aeruginosa as a model for Gram- negative bacteria and Staphylococcus aureus as a model for Gram- positive bacteria. Minimum inhibitory concentration (MIC) of antibacterial silver nanoparticles that were biologically synthesized using Moringa oleifera leave extract was tested to estimate the effect of nanoparticles on cell viability, cell integrity, and cell permeability of tested bacteria. The results indicated that there was a great effect of AgNPs on cell viability of bacterial strains tested as there was significance in growth kinetics between control and treated bacteria with silver nanoparticles. Also, cell permeability of S. aureus and P. aeruginosa were greatly affected by biologically synthesized silver nanoparticles and statistical analysis revealed that there was significant difference in cell permeability of two tested bacteria between control and treated cells with nanoparticles. However, there were slightly effect of these nanoparticles on cell integrity when the absorbance of DNA was estimated.