The article presents the results of study of qualitative and quantitative indicators of phytoplankton of the Dniester River within the Republic of Moldova in 2015-2016. In phytoplankton compositions of the Dniester River were identified 81 species. Seasonal and long-term of phytoplankton have been established in middle and lower section of the Dniester River. The numbers of phytoplankton changed within the limits 1,49 to 16,26 mln. cel/l with biomass 1,96-9,38 g/m3 in the spring, from 1,16 to 19,42 mln. cel/l with biomass 1,16-15,31 g/m3 in the summer, and from 1,23 mln. cel/l to 18,46 mln. cel/l with biomass 0,95-8,32 g/m3 during autumn. The values of saprobic indexes, estimated on the basis of species-indicators (52 species) from phytoplankton composition, which are in proportion of 60% typically β-mezosaprobic, confirm the following: the water quality of Dniester River in the period 2015-2016 was satisfactory for the development of phytoplankton and was attributed mainly to II-III (good-moderately polluted) quality classes.