The mycosynthesis approach for nanoparticle synthesis using edible mushrooms is attracting considerable interest over other conventional physical and chemical methods because this approach excludes the use of toxic chemicals. The present study reports the biological synthesis of silver nanoparticles (AgNPs) using an aqueous extract of Pleurotus djamor var. roseus and its cytotoxicity against human prostate carcinoma (PC3) cells. Nanoparticle formation was confirmed by UV-visible (UV-vis) spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FFIR) analysis. The UV-vis spectrum had an absorption peek at 440 nm, corresponding to the surface plasmon resonance of AgNPs. The TEM image confirmed the nanostructure and spherical shape of AgNPs, with sizes ranging from 5 to 50 nm. The FTIR spectroscopy results showed the binding properties of bio-constituents to identify the possible biomolecules responsible for capping and efficiently stabilizing the nanoparticles. The purity and crystalline structure were confirmed by XRD analysis. Furthermore, the cytotoxicity of biosynthesized AgNPs was evaluated using cell viability and nuclear fragmentation assays. It is evident from the results that the biosynthesized AgNPs inhibited proliferation of PC3 cells with an IC50 of 10 mu g/ml during a 24-h incubation. These results suggest that AgNPs may exert their antiproliferative effect on the PC3 cell line by suppressing its growth, reducing DNA synthesis and inducing apoptosis. The morphological analysis of propidium iodide (PI) staining showed the presence of shrunken nuclei, DNA condensation and damage, which revealed cytotoxic effect on PC3 cells by AgNPs. (C) 2014 Elsevier Ltd. All rights reserved.