Saccharomyces cerevisiae, Rhodotorula glutinis and Geotrichum candidum were selected for biosgenesis of silver nanoparticles (AgNPs) using yeast reductases. Extracellular proteins act as stabilizers for so formed AgNPs. Factors affecting biosynthesis ; biomass concentration, AgNO3 concentration and the ratio of AgNO3: to biomass concentration on. The Optimum conditions for biosynthesis of AgNPs could be attained using biomass of Saccharomyces cerevisiae (3 mL/100 mL): .9 mM AgNO3: pH 12: 25 ◦C and 24 h incubation). Under these conditions, the maximum concentration of well stabilized AgNPs obtained was 900 ppm with a mean diameter range of 1.5–12 nm. Such solution is unequivocally feasible for industrial applications.