The control of biodegradation rate is even more important than the characteristic of biodegradability itself. This is the reason why it is critical to find additives able to modulate the biodegradation rate of biodegradable polymers in relationship to the expected lifetime. This paper reports the effects of silver nanoparticles (AgNP) on the biodegradation behavior of the poly(lactic acid) (PLA). Different amounts of AgNP (0.01; 0.07; 0.12 wt%) were melt mixed with a commercial PLA in order to analyze their effect on the composites properties. The composites were submitted to biodegradation tests in controlled composting conditions, according to ASTM D 5338 and ISO14855 standards. Thermal properties of PLA and composites were analyzed at different biodegradation times. The aim was the tuning of the biodegradation rate of PLA by the addition of silver nanoparticles.