We found 77 species of myxomycetes in the oak and pine forests of the National Nature Park Slobozhanskiy in northeastern Ukraine. Among them, Arcyria imperialis, Didymium ovoideum, Lamproderma gulielmae, Trichia subfusca, Oligonema fulvum and Physarum spectabile are new for Ukraine. In addition, a specimen, preliminary identified as Arcyria cf. bulbosa, may represent a species new to science.