Streptomyces is the most widely studied and well-known genus among actinomycetes. Streptomycetes, due to their extracellular enzymes, have a great potential for the biodegradation of organic and inorganic toxic compounds. Several studies have demonstrated the ability of streptomycetes to grow and degrade several chemical families of pesticides, including organochlorine, organophosphorous, polyaromatic hydrocarbons. Last decade streptomycetes are successfully used in the synthesis of metal nanoparticles, especially of silver and gold, less of manganese, zinc and copper nanoparticles. Among metal-based engineered nanomaterials, iron nanoparticles (NPs) are, probably, the most used for bioremediation of a broad spectrum of pollutants. Iron-based NPs are expected to be nontoxic, due to using Fe atom in several pathways of cell metabolism and, therefore, low iron toxicity. But there is a series of investigations that prove the toxic action of iron NPs on different microorganisms. Regarding the interaction between iron NPs and streptomycetes, there is a little information in specialized literature, but the existing data attests the resistance of streptomycetes to the action of iron NPs. The present study aims to determine the impact of magnetite NPs and zero-valent iron (ZVI) NPs on growth of Streptomyces strains. Streptomyces strains were isolated from soil longterm polluted with obsolete pesticides, DDT and trifluralin. Encapsulated NPs were synthesized by chemical co-precipitation method, in the presence of poly-N-vinylpyrrolidone (PVP) used as a stabilizer. Magnetite NPs were prepared using iron (II) sulfate and iron (III) chloride. ZVI NPs were prepared by chemical reduction from ferric chloride solution. The inhibition activity of magnetite and ZVI NPs was evaluated using express-method. Each streptomycete strain had an individual reaction to the solutions of iron NPs. Sensitivity of the strains varies depending on the chemical form of NPs and the individual peculiarities of each strain. In most cases, both magnetite and ZVI NPs had a stimulating effect on the growth of streptomycetes, ZVI NPs had no inhibitory effect on their growth. Most of the studied streptomycetes were found to be sensitive to trifluralin, fluorinated dinitroaniline herbicide. Mixing the solutions of iron NPs and trifluralin resulted in the reduction of trifluralin toxicity.