Chitosan nanoparticles (CS-NP) containing small silver nanoparticles are reported (Ag@CS-NP). CS-NP was synthesized using tripolyphosphate (TPP) as a polyanionic template. TPP also served to electrostatically attract Ag + inside CS-NP, where it was reduced by the terminal glucosamine units of the biopolymer. This procedure is environmental friendly, inexpensive, and permits the synthesis of very small AgNP (0.93–1.7nm), with only a discrete dependence from the amount of silver nitrate used (5–200mg). The obtained hybrid nanocomposites Ag@CS-NP were characterized by DLS, HRTEM, and HAADF–STEM presenting a mean hydrodynamic diameter of 78nm. The antimicrobial activity of Ag@CS-NP against Candida glabrata, Sacharomyces cerevisiae, Escherichia coli, Klebsiella pneumoniae, Salmonella, Staphylococcus aureus, and Bacillus cereus corresponded to MIC values lower than for AgNO 3 .