A study of fungi on Amaranthus spp. was performed in 2007-2009. The following forms of the genus were taken under consideration: cultivated amaranth (A. cruentus) and a wild form (A. retroflexus) growing as a weed on amaranth and sugar beet plantations and growing as a ruderal weed. The aim of the work was to determine which fungi communities occur in the phyllosphere, roots, rhizoplane, and rhizosphere of Amaranthus spp. To investigate the phyllosphere fungi communities, 5 plants were taken in the seed formation phase. From each plant, 3 healthy, symptomless leaves were taken. In addition, the isolation of fungi communities from the roots, rhizoplane, and rhizosphere was performed in the seed formation phase. Ten plants from each location were taken along the diagonal of the plot. In total, 38 species of fungi were isolated from the phyllosphere of Amaranthus spp., and of that number, 30 were collected from A. cruentus and 29 from A. retroflexus. In total, 29 fungi species were isolated from the roots of all the observed forms of amaranth. From the rhizosphere of all amaranth species tested, 44 fungi species were isolated. The most frequently recorded taxa within the associations of fungi isolated from the phyllosphere were Cladosporium spp. (C. cladosporioides and C. herbarum), Alternaria alternata, and Epicoccum nigrum. Fungi species of the genera Penicillium, Fusarium, Cladosporium, and Phoma, as well as species of A. alternata, were isolated in great abundance from the roots and the rhizosphere of the amaranth plants.