Bardawil Lagoon is a shallow hypersaline lake, with salinity ranging between 38.0 and 56.0. It is a source of good quality fish and wildlife. The phytoplankton and zooplankton were evaluated seasonally at 12 sta-tions during 2015. The water temperature was 22.14 ± 4. 98°C and water salinity was 47.93 ± 5.01. The dissolved oxygen was 5. 14 ± 0.83 mg l-1. The recognized phytoplankton species were 181 taxa from 83 genera and seven clas-ses were recorded. This comprised; 101 Bacillariophyceae, which formed 84.48 % of the total phytoplankton stand-ing crop, 13 Chlorophyceae (6.14 %) and 46 Dinophyceae (5.75 %). TheShannon–Wiener Diversity Index (0.48–3.35) classified Bardawil Lagoon as a not stressed environment. Zooplankton population was represented by 59 genera and 77 species from 16 groups, mainly dominated with Copepada (62.71% of the total community), followed by Mollusca (24.44%) and Protozoa (6.9%). The diversity index ranged from 0.97 to 2.27.The present study, as well as previous research, revealed strong ties between changing structures in plankton communities and salinity. No sign of eutrophication was observed. Results showed an inverse relation between two of the identified communities. The study showed that Bardawil water is still oligotrophic, free of contaminants,so we recommend to dig two or three canals, to facilitate the exchange of water between the Mediterranean Sea and the Lagoon, and to prevent the increase in water salinity of the Lagoon.