In this work, we propose a simple and cost effective colorimetric method for the detection of Pb2+ using silver nanoparticles (AgNPs) prepared from the leaf extract of Aconitum violaceum. Due to the presence of significant amount of polyphenols in the extract, the AgNPs were successfully synthesized and were then characterized by UV vis spectroscopy, Fourier transform infrared spectroscopy (FT-IR), X-Ray diffraction (XRD) and transmission electron microscopy (TEM). The as prepared AgNPs were employed as colorimetric probes for the detection of Pb2+. In the presence of Pb2+, the biosynthesized AgNPs showed a color transformation from yellow to red, which was readily determined by UV-vis spectroscopy. The novel sensor exhibited good linearity for the detection of Pb2+ in the concentration range of 0.5 - 25 mu M (R-2 = 0.996) with a detection limit (LOD) of 0.1 mu M. Also, this sensing system presented a highly selective response for Pb2+ determination.