Medical applications require, in most cases, antibacterial protection. The use of silver (Ag) gives important antibacterial properties since silver is highly toxic for bacteria. In this research work, we have used silver nanoparticles (Ag NPs) with different surfactants, polyvinyl pyrrolidone (PVP) and oleic acid (OA) to facilitate dispersion. PP-Ag NPs compounds were prepared by melt mixing, and the effects of the processing conditions on nanoparticles' dispersion were investigated by transmission electron microscopy (TEM). The antibacterial efficiency of PP-Ag NPs compounds against Staphylococcus aureus ATCC 6538 and Escherichia coil ATCC 8379 was evaluated. Results show that good dispersion is obtained with rotating speeds in the 350-500 rpm range. TEM analysis reveals balanced dispersion and presence of some Ag NPs aggregates. Regarding antimicrobial properties, the use of PVP as surfactant leads to 'significant' antimicrobial activity of 1.5 against Staphylococcus aureus and Escherichia coil; on other hand, the use of oleic acid (OA) as surfactant leads to strong protection against Staphylococcus aureus (antimicrobial activity between 2.5 and 3.3) but the overall protection against Escherichia coil is very low (lower than 1). Results show that the use of surfactants for Ag NPs has important effects on antibacterial properties of polypropylene filled with coated Ag NPs. POLYM. ENG. SCI., 51:804-811, 2011. (C) 2011 Society of Plastics Engineers