Fungi are more versatile in growth and metal tolerance in contrast to bacterial population. Hence they have been used as biofactories for synthesis of nanoparticles. Nanoparticles offer environment friendly solutions for different problems. In present study, biofabrication of silver nanoparticles was carried out from soil isolate Aspergillus niger. The extracellular silver nanoparticles present in fungal filtrate were characterized by various analytical techniques. Upon exposure of the fungal filtrate to silver nitrate, the latter was reduced to silver nanoparticles as indicated by a color change observed by UV-visible spectroscopy. Absorbance was recorded from 300-600 nm and a strong absorbance peak was observed at 430nm. Silver nanoparticles subjected to X-ray diffraction crystallography revealed four peaks at 38, 48o, 64o and 72o at 2 values and correspond to face centered cubic (FCC) nanocrystals. AFM findings showed the silver nanoparticle aggregations. SEM results strongly revealed their surface topography. The optimum experimental conditions were found to be a temperature 37oC, a pH of 6.0 and a substrate concentration of 2.0mM.