Silver nanoparticles have been prepared by the reduction of the corresponding metal salt with NaBH 4 in the presence of appropriate dispersing agents, namely, copolymers of maleic acid with N-vinylpyrrolidone, ethylene and styrene or their amphyphi- lic derivative containing octadecylamide ligands. The silver colloids identified by optical absorption spectroscopy were synthesized when the copolymer concentrations were lower than their critical aggregation concentrations and copolymer/Ag+ molar ratio no greater than a unit. According to the data of transmission electron microscopy, the obtained Ag nanoparticles were spherical-shaped particles 1—2 nm in size. Colloidal solutions of the prepared nanosilver showed a strong inhibiting antifungal activity against a fungal plant pathogen Fusarium oxysporum and also Gram-negative, Gram-positive bacteria and yeast. The silver nanoparticles stabilized with more hydrophilic compounds from among the investigated copolymers demonstrated the higher antibacterial and antifungal activity.