Abstract: Fungal pathogens pose serious problems worldwide for both human and animal health and their toxin are natural contaminants of foods and feeds. Streptomyces had bioactive substances that demonstrated inhibitory affects against pathogenic and toxic fungi. The focus of this study was on the antimicrobial and inhibitory activities of Streptomyces. Streptomyces isolates obtained from different area in Al-Muzahimiyah in Riyadh Region at Saudi Arabia. Six different isolates were evaluated for their antimicrobial activity against different microorganisms. A laboratory studies was carried out on tested isolates of Streptomyces to determine their effect on toxigenic isolate of F. verticillioides. Out of the tested Streptomyces isolates, only RS-4, WS-1, GS-2 and BS-5 showed antimicrobial activity. According to antagonistic and dry weight trials it was found that all of the tested Streptomyces isolates had inhibitory effect on the toxigenic isolate of F. verticillioides especially (RS-4 followed by WS-1 and GS-2). There was strong inverse relationship between antagonism activity of tested Streptomyces isolates and total dry weight of indicator microorganisms. A significant reduction in zearalenone and fumonisin was recorded after 7 days of incubation. Also, Streptomyces isolates No. RS-4 was the most effective one followed by WS-1 and GS-2 and the reduction ratio was 65.8, 52.6 and 447%, for zearalenone while for fumonisin was 62.5, 45.8, 37.5%, respectively. In conclusion, some Streptomyces were isolated from ecosystem soil. These Streptomyces isolates were differed in their morphological and antagonistic characteristics. Some of these isolates have a significant impact in reducing mycotoxins which secreted by F. verticillioides.