Data on the first recorded marine alga Prorocentrum leve Faust, Vandersea, Kibler, Tester & Litaker (Dinophyceae) in a Russian inland waterbody, the hypersaline Lake Manych-Gudilo, are given. As a result, in May, July, and October 2016 and February 2017 it was revealed that the species was found in small quantities, mainly in the northwestern part of the lake. Its morphology, studied with an electron scanning microscope, is largely consistent with that described in the literature. The presence of marine species P. leve can serve as indirect evidence of the fragmentation of marine algal areas as a result of paleobasin regression. The results expand information on the composition of the algal flora of inland water bodies in Russia, as well as on the environmental opportunities and general distribution of P. leve.