Information about the history of knowledge on zooplankton in rivers of theRepublicofKarelia(drainage basins ofLakeOnego, the northern part ofLakeLadoga, theWhite SeaKarelianCoastand theWhite SeaPomorCoast) was systematized. The studies were carried out by research institutions of theKarelianRepublicandNorthwest Russia. The implemed basic and applied research included analysis of the species diversity, quantitative indicators, condition of zooplankton formation, and evaluation of changes in zooplankton communities under natural and human impacts.