Green synthesis of metal nanoparticles has gained great attention due to the need for safe, cost-effective and eco-friendly technologies for metal nanoparticles synthesis. Fungi have been represented as a novel field of study in nanotechnology. This study was focused on extra/intracellular synthesis of highly stable silver nanoparticles (SNPs) using aspergillosis causing fungi. Four strains of opportunistic fungi isolated from aspergillosis suspected patients at Assiut University Chest Department A. flavus KY609551, A. fumigatus MT994683, A. niger KY609552 and A. terreus MF852635 were kindly provided by Enas M. Amer, Faculty of Science of Assiut University tested for their ability to synthesize SNPs extra/intracellularly. Exposure of fungal cell filtrate to 1 mM of aqueous Ag⁺ ions resulted in reduction of the metal ions and formation of silver nanoparticles. Visual observation showed the ability of the three different fungi namely A. flavus KY609551, A. fumigatus MT994683 and A. terreus MF852635 to produce SNPs. However, A. niger KY609552 could not gave SNPs at 1 mM of aqueous Ag⁺ ions. The bioreduction of SNPs was monitored by ultraviolet-visible spectroscopy, and the SNPs obtained were characterized by Fourier Transform Infrared Spectroscopy (FTIR) and X-ray diffraction. UV - visible spectra demonstrate a strong, quite narrow peak located between 435 and 450 nm was obtained in case of A. flavus KY609551 and A. terreus MF852635, respectively. Whereas a wide peak centering at 435 nm in case of A. fumigatus MT994683. To prepare the X-ray diffraction and FTIR for samples, a modified simple technique for extracting SNPs from aqueous solution using chloroform was used. It is the first time to be reported that used chloroform as an extract of SNPs from their aqueous solution, to facilitate FTIR and X-ray examination. X-ray diffraction confirmed the formation of metallic silver. FTIR spectroscopy analysis showed the presence of an amide group which appears to be responsible for biosynthesis and stability of nanoparticles for both A. flavus KY609551 and A. terreus MF852635.