Liman lake is a part of the Kiziirmkak Delta which is one of the most valuable wetland systems in Northern Turkey as a Ramsar site. Liman Lake is a typical brackish lagoon lakewhich is separated from the Black Sea by a narrow sandy barrier. Phyto/zooplankton composition, chlorophyll aand some water quality parameters were investigated in the mixo-oligohaline brackish Liman lake between October 2002 and March 2004. Water temperature, oxygen, Electrical Conductivity (EC), pH and salinity, chemical parameters (K(+), Na(+), Mg(2+), Ca(2+), Cl(-), SO(4)(2-), HCO(3)(-) and CO(3)(2-)) and nitrite, nitrate, ammonia and orthophosphate were analyzed. About 35 taxa were distinguished in the zooplankton samples (Rotifera 28, Cladocera 5 and Copepoda 2). Hexathra oxyuris, Keratella quadrata, Keratella cohlearis were dominant species. A total of 73 species belonging to Cyanobacteria (25), Chlorophyta (23), Bacillariophyta (14), Pyrrophyta (5), Cryptophyta (3) and Euglenophyta (3) were identified. Chroococcus minutus, Merismopedia tenuissima, Phormidium tenue, Phormidium sp., Monoraphidium contortum, M. minutum, M. pusillum were perennial dominant species. The chlorophyll a concentration of Liman lake ranged from 5-50 mu g L(-1) with a mean value of 19.7 mu g L(-1). Based on chlorophyll a results, the trophic level of Liman lake was found in the range of eutrophic level.