In order to increase the biosynthetic potential of microorganisms of biotechnological interest, nanotechnology is widely applied. Areas of application of nanotechnology have become: medicine, pharmacology, biotechnology, production and processing of agricultural products, agricultural engineering, technical service, etc. The purpose of the research was to evaluate the action of Fe nanoparticles (NP) on filamentous fungi.20 strains of micromycetes from the National Collection of Non-pathogenic Microorganisms belonging to the genus: Aspergillus (5), Trichoderma (5) and Penicillium(10) served as the object of the study. The action of NP: Fe2O3 (2-10 nm), Fe2ZnO4 (8-15 nm), and Fe2CuO4 (20-30 nm) has been studied on growth, morpho-cultural characteristics and antifungal activity of mentioned strains. The microbicids were cultured on both Czapekagarized and submersed media and the Czapek medium supplemented with NP of Fe2O3, Fe2ZnO4 and Fe2CuO4 at a concentration of 0.001%. Cultivation on agarizedCzapek medium was carried out on Petri dishes for 10-14 days at 28-30°C, after which the morpho-cultural characteristics of the strains were examined visually and microscopically. The submerged cultivation was carried out in 250 mL Erlenmeyer flasks on a shaker, speed-rotating 180-200 r.p.m. at 28-30°C for 6 days. As an inoculum, a volume of 5% spore suspension of 5x106 cells/mL of the studied cultures was used. As a control the sample was investigated without application of NP. Separation of the biomass from the culture fluid was performed by filtration and gravimetrically calculated. The amount of biomass obtained was calculated per liter of the liquid medium. The antifungal activity of the strains, belonging to the genus Penicillium and Trichoderma, was determined by the agglomeration method of the agar, after the diameter of the phytopathogen growth inhibition zone. As test strains phytopathogens were studied: Aspergillus niger, Alternariaalternata, Botrytis cinerea, Fusariumsolani, Fusariumoxysporum. Experiences were performed in 3 repetitions. Data processing was done using MS Office Excel 2010. The results obtained have shown that in the cultivation of micromycetes on the agar medium supplemented with NP of Fe2O3, Fe2ZnO4 and Fe2CuO4, significant changes in the studied cultures are not produced. Some changes in the order of color or colony size have been recorded in some strains. In the submerged cultivation of Trichoderma strains in Czapek supplemented with NP of Fe2O3, Fe2ZnO4 and Fe2CuO4, the growth was at the control or diminished variant. NP of Fe2O3, Fe2ZnO4, and Fe2CuO4 have been more beneficial for the growth and accumulation of biomass of strains belonging to the Penicillium genus. The mean value of this index varied within ± 15% of the control, more significant increases was obtained in the NP Fe2O3 and Fe2ZnO4 variants. Also, the use of NP Fe2ZnO4 in the microbicide culture medium of Penicillium and Trichoderma species significantly stimulates their antifungal activity against phytopathogens. Pathogen inhibition zones exceed the control variant by 5-30%. In conclusion, the NP of Fe2O3, Fe2ZnO4 and Fe2CuO4 used in the cultivation of micromycetes belonging to Aspergillus, Penicillium and Trichoderma genera can modify their morpho-cultural and biosynthetic properties and therefore can be used in biotechnology.