Silver nanoparticles (SNP) were fabricated by method of chemical reduction of silver ions to Ag(0) in aqueous solution in the presence of surfactant micelles. Hydrazine hydrate was used as a reducing agent. Solution of SNP had brown-yellow color; median linear size of SNP was approximately 35 nm: and they showed absorption maximum at 420 nm. Toxicity of the SNP was tested in E. coli K802 cells. The particles displayed antimicrobial activity. Effect of SNP on mammalian copper metabolism was tested in mice. Atomic silver was found in blood serum, it was taken up by hepatocytes, inserted to active centers of ceruloplasmin, secreted to blood, and excreted through bile and urine. After cancellation of the SNP injections, silver concentration decreased in extracellular fluids. It is likely that SNP were corroded to form Ag(I), which integrated to copper turnover. The effects of silver intervention in copper metabolism of mammals as well as using SNP to trace copper transfer are discussed.