This study was carried out seasonally in 9 stations selected to represent the lake in between April 2013 and January 2014. Physicochemical water quality analyzes were carried out in order to determine water quality parameters of Egirdir Lake. Water temperature, dissolved oxygen, oxygen saturation, pH, electrical conductivity and salinity parameters were measured in situ. Turbidity, chemical oxygen demand (COD), sulphate (SO4-2), carbonate (CO3-2) and bicarbonate (HCO3-2) alkalinity, calcium (Ca+2), magnesium (Mg+2), total hardness (TS), ammonium (NH4(+1)), potassium (K+1), sodium (Na+1), silicon (Si+1), nitrite (NO2-1), nitrate (NO3-1) and orthophosphate (O-PO4-3) were determined by titrimetric and spectrophotometric methods in the laboratory. On the average of the parameters in the obtained; water temperature 14,2 oC; dissolved oxygen 9,05 mg/L; pH 8,78; saturation 90,0%; electrical conductivity 383,4 mu S/cm and salinity 0,28 ppt as was determined. Parameters performed in the laboratory, on average, the turbidity 1,08 NTU; COD 17,0 mg/L; SO4-2 26,57 mg/L; O-PO4-3 0,05 mg/L; NH4+1 0,035 mg/L; NO 21 0,032 mg/L; NO3-1 1,2 mg/L; CO3-2 alkalinity 21,1 mg/L; HCO3-2 alkalinity 197,55 mg/L; Ca+2 23,46 mg/L; Mg+2 34,80 mg/L; TS 20 F-o; K+1 2,82 mg/L; Na+1 9,57 mg/L and Si+1 1,215 mg/L as was determined. As a result of the study, it was determined that water quality of Egirdir Lake is Class I water quality (High quality water) in terms of physical and some chemical parameters according to inland water quality standards. However, attention has to be paid to nitrogen and phosphorus. In this context, it is necessary to apply a good protection-use plan and program according to the characteristics of the basin and to take the necessary precautions in order to protect the lake.