The results of floristic studies of algal diversity of 12 rivers of the Kiev Upland Region (Ros, Stugna, Krasnaya, Rosava, Uzynka, Rokytka, Siverka, Kozynka, Bobritsia, Bezymyannaya, Gorokhovatka, Protoka) are given in the article. There are 493 species (511 ist). The basis of the taxonomic structure of the algae is formed by Bacillariophyta (39.7%), Chlorophyta (27.8%), Euglenophyta (10.7%), Cyanoprokaryota (9.3%). The contribution of the remaining orders to the diversity did not exceed 12.4% of the total number of species. Distribution of species in rivers is uneven. The largest number of species is characteristic for the Ros River, the least – for the Siverka River. For the assess of representativeness of species composition in watercourses, the coefficient of the floral’s community was used. The greatest degree of similarity of the species composition of algae is characteristic for 3 pairs of rivers: Ros and Stugna (0.41), Siverka and Bezymyannaya (0.40), Protoka and Uzynka (0.36). The Encyonema neomesianum Krammer (= Encyonema minutum var. pseudogracilis (Cholnoky) D.B. Czarnecki) and Navicula microrhombus (Cholnoky) Schoeman et Archibald are new record for algalflora of Ukraine. Among revealed diversity, 9 species are first cited for the Middle Dnieper Algofloristic Subprovinces: Amphora inariensis Krammer, Cylindrospermopsis raciborskii (Wołosz.) Seenayya et Subba Raju., Craticula subminuscula (Manguin) Wetzel et Ector (= Eolimna subminuscula (Manguin) Gerd Moser, Lange-Bertalot et Metzeltin), Diploneis elliptica (Kütz.) Cleve, Eunotia crista-galli Cleve, Navicula erifuga Lange-Bert., Stephanodiscus neoastraea Håkansson et Hickel, S. parvus Stoermer et Håkansson and Radiococcus planktonicus J.W.G. Lund. A further 14 rare species for the Middle Dnieper Algofloristic Subprovinces are recorded: Cyclotella atomus Hustedt, Discostella pseudosteligera (Hustedt) Houk et Klee, Gomphonema laticollum E. Reichardt, Fallacia subhamulata (Grunow) D.G. Mann, Navigeia decussis (Østrup) Bukht., Planktolyngbya contorta (Lemmerm.) Anagn. et Komárek., Pseudanabaena redekei (Goor) B.A. Whitton (= Limnothrix redekei (Van Goor) Meffert.), Pseudostaurosira subconstricta (Grunow) Kulokovskiy et Genkal, Staurosira binodis (Ehrenb.) Lange-Bertalot, S. construens var. subsalina (Hust.) Gerasimiuk, S. venter (Ehrenb.) Cleve et J.D. Möller, Stephanodiscus delicatus Genkal, Staurosirella pinnata (Ehrenb.) D.M. Williams et Round, Surirella librile (Ehrenb.) Ehrenb.
Keywords: algae, species diversity, new species, new record, Kiev Upland, the Middle Dnieper Algofloristic Subprovince