The antimicrobial activities of silver nanoparticles biosynthesized using extracts of Piper betle L. leaves (AgPBL) and mulberry leaves (AgMul) were compared against four bacteria (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Micrococcus luteus) and two fungi (Candida albicans and Aspergillus niger) using the well diffusion and disc diffusion methods. The biosynthesized AgMul and AgPBL were observed at 453nm and 442nm, respectively, via UV-Vis spectra analysis. Morphological characterization using TEM revealed the former to possess spherical particle sizes of 15 - 40nm, whereas the latter exhibited sizes of 10 - 20nm. The results showed that the antibacterial activity of two types of silver nanoparticles, at concentrations of 100 and 50μg/mL, was significant against four bacterial strains, and was also effective against the yeast Candida albicans. According to the obtained zone of inhibition results, an obvious superiority of the antimicrobial potency was observed for AgMul in comparison to AgPBL. In addition, the AgPBL exhibited potent activity against the mold Aspergillus niger. The antimicrobial assays results indicated that the biosynthesized AgMul and AgPBL have the potential to be used for the antibacterial and antifungal treatment of textiles and leather materials.