Silver(I) complexes are known to have antimicrobial activities; however, many of them have been reported to show a different antimicrobial spectrum against microorganisms from the ligand itself and the hydrated silver(I) ion. During an investigation of the structural relationship of silver(I) complexes with anti-microbial activities in aqueous media, we noticed that the key factor determining the antimicrobial effects is the kind of atom coordinated to Ag+ and its bonding properties, rather than the solubility, charge, chirality, or degree of polymerization of the silver(I) complexes. Generally, silver(I)-S complexes show a narrower spectrum of antimicrobial activities than silver(I)-N and silver(I)-O complexes. Most of the silver(I) complexes with silver(I)-P bonds investigated have shown no antimicrobial activity. Although silver(I) complexes having only silver(I)-N and silver(I)-O bonds show potential antimicrobial activities against many microorganisms, most of them are insoluble in commonly used solvents or are light-sensitive, especially in solution and, therefore, their characterization is rather difficult.  Recently, we found that several ligands afforded water-soluble and relatively light-stable (i.e., stable for a few hours to days at ambient temperature) silver(I)-N and silver(I)-O complexes. This article describes the choice of ligands, synthetic procedure and characterization of water-soluble silver(I) complexes having effective antimicrobial activities.