This work compares the characteristics and antimicrobial activity of chemically- and green-synthesized silver nanoparticles (Ag-NPs). The Ag-NPs were characterized using UV-visible spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR) analyses, Transmission electron microscopy (TEM), and Zeta Potential (ZP). Results revealed that chemically synthesized Ag-NPs (C-Ag-NPs) were spherical with a particle size range of 4.86 to 13.6 nm, while the green-synthesized Ag-NPs (G-Ag-NPs) were of multi-shapes and size- range of 38.9 to 103 nm. Zone-inhibition test was done to compare the antimicrobial activity of both versions against common microbes of hatchery machines such as: G+ bacteria (Bacillus cereus, Bacillus subtilis, Staphylococcus aureus and Methicillin-resistant Staph. aureus (MRSA), G- bacteria (Escherichia coli O157; Pseudomonas aeruginosa, and Salmonella typhimurium), Mold (Aspergillus niger) and yeast (Candida albicans). Generally, both C-Ag-NPs and G-Ag-NPs had significant effects on the tested microbes. The antibacterial effect of G-Ag-NPs against Ps. aeruginosa, B. cereus, and MRSA was significantly stronger than that of C-Ag-NPs, while the antifungal effect of C-Ag-NPs against Aspergillus niger was superior over that of G-Ag-NPs. For application, G-Ag-NPs and TH4 (a commercial disinfectant of poultry facilities) were separately sprayed onto the wall of egg incubators to compare their effect on total aerobic counts, total spore counts and total fungi. Results showed that both G-Ag-NPs and TH4 had strong effects on total aerobic counts, total spore-counts, and total fungi. G-Ag-NPs indicated higher efficacy than TH4. It could be concluded that G-Ag-NPs may be a promising antimicrobial candidate for sanitizing poultry facilities.