As propriedades da prata sao conhecidas ha muitos anos. Recentemente, as nanoparticulas de prata tem chamado a atencao por sua atividade antimicrobiana que oferece a possibilidade de uso com propositos medicos e de higiene. Estas nanoparticulas de prata em diferentes formulacoes, com diferentes formas e tamanhos, exibem atividades antimicrobianas diferentes. Entretanto, os mecanismos da atividade antimicrobiana de ions e de nanoparticulas, assim como sua toxicidade em tecidos humanos nao estao totalmente esclarecidos. Esta revisao avalia o uso potencial de nanoparticulas de prata no controle de patogenicos com enfase sobre sua acao contra bacterias patogenicas, sua toxicidade e possiveis mecanismos de acao. The antimicrobial properties of silver have been known for thousands of years. Recently, silver nanoparticles have gained attention because of their antimicrobial activity which offers the possibility of their use for medical and hygiene purposes. Indeed, silver nanoparticles in different formulations and with different shapes and sizes exhibit variable antimicrobial activity. However, the mechanisms of antimicrobial activity of silver ions and silver nanoparticles, and their toxicity to human tissues are not fully characterized. This review evaluates the potential use of silver nanoparticles to control pathogens with emphasis on their action against pathogenic bacteria, their toxicity and possible mechanisms of action.