Widely use of antibiotics resulted in increase of antibiotic resistance bacteria. These bacteria cause diseases that respond poorly to medications. Individuals infected with multidrug resistant (MDR) bacteria are prone long periods of hospitalization. Thus the emergence of antibiotic-resistant bacteria that pose threat to human life becomes a major public health concern. In this book, Ag-nanoparticles were synthesized by mixing AgNO3 with suitable amount of plant extracts. Bactericidal activities of Ag-nanoparticles were tested against human pathogenic bacteria. The mechanism of action by which Ag-nanoparticles affected bacteria was investigated by SEM analysis in comparison with a negative control. Bacteria treated with Ag-nanoparticles appeared to be shrunk and lost their viability. Finally, this book presents a cheap and effective method for synthesizing Ag-nanoparticles and their use against human pathogenic bacteria.