The effect of different levels of sodium chloride (NaCl) on water and feed intakes, milk yield and its composition and some physiological responses in Friesian cows was examined in this study during the three months of summer season (June, July and August). A total of 25 cows averaging 482.4±20.5 kg LBW, ranging 41-76 months of age and 2- 4 parities was used. All cows were at post-partum period after 25 days of calving. The cows were divided equally (five animals) into five groups according to their LBW, parity and its milk production. The 1^st group cows were fed a basal diet without any treatment, that were considered as a control group (G1), and the cows in the three groups (G2), (G3) and (G4) were received a daily drinking water containing NaCl as 2000, 5000 and 7000 mg/l, respectively, during the experimental period. While, the 5^th group cows (G5) were received drink water containing 2000, 5000 and 7000 mg/l NaCl during the first, the second and the third months of the experiment, respectively. Results showed that rectal temperature values (RT, ^oC) were significantly (P<0.05) lower in groups G3, G4 and G5 than in groups G1 and G2 in June, July and August, and the lowest value was in group G3 in June month. Values of white skin temperature (^oC) and respiration rate were significantly lower in groups G3, G4 and G5 than in groups G1 and G2. And values of black skin temperature (^oC) were significantly lower in groups G2, G3 and G5 than in groups G4 and G1. Water intake values of the treatment groups were significantly (P<0.01) higher than the control group as follows 12.3, 30.56, 54.49 and 18.6% in G2, G3, G4 and G5, respectively, where the highest value of the water intake was in group G4. Total dissolved solids (TDS) of SO₄, CO₃, Cl, Na and Ca were significantly (P<0.01) higher in treated groups than in the control group, TDS were increased with the increased amount of salt in the drinking water. Concentration of total protein, albumin and globulin in blood plasma were not significant.  Glucose concentration was higher significantly (P<0.05) in G4 and G5 than the control group. The effect of NaCl treatment in drinking water on daily milk production as actual milk yield, fat corrected milk (FCM) as well as fat and protein yields in G3 and G4 tended to be significantly higher than the control and other treatment groups (G2 and G5). Milk composition was not affected by salt treatments. Cows in groups G3, G4 and G5 showed significantly (P<0.05) lower somatic cell counts (SCC) in milk yield as compared with G1 and G2 groups. Conclusively, the obtained results recommend common salt addition to the drinking water at 5g/L to improve the performance and production in Friesian lactating cows.