Vrana Lake near Biograd na Moru is a karst field filled with water and is the largest natural lake in Croatia. It was declared a nature park in 1999, mostly because of the ornithological reserve in its area. An important part of the Vrana Lake ecosystem is zooplankton, and it includes three predominant groups: Rotifera, Copepoda and Cladocera. Zooplankton plays a significant role in lake ecosystems, especially in determining the ecological status of lakes. The goals of the research were: (i) to determine the abundance, biomass and diversity of zooplankton; (ii) to study the influence of biotic and abiotic factors on zooplankton dynamics; (iii) to study the impact of fish predation on zooplankton dynamics; (iv) to assess the impact and importance of zooplankton in lake ecosystems. In the period from April to November 2018 and 2019, zooplankton samples were taken at three stations, and for the analysis of the influence of abiotic and biotic factors on the dynamics of zooplankton, certain physicochemical factors were observed and analyzed. The research revealed a significant influence of temperature, salinity, dissolved oxygen, transparency and a significant influence of ichthyofauna on the structure and dynamics of zooplankton. The study of the influence of biotic and abiotic factors on the dynamics of zooplankton will provide insight into the trophic state of the lake, which will enable the determination of guidelines for further management of Vrana Lake and protection of this valuable and important habitat.