The aim of this study was to assess live body weight (LBW), percentages of total body fluids (TBF), extracellular fluids (ECF), intracellular fluids (ICF), plasma volume (PV), and concentrations of aldosterone (ALD), sodium (Na) and potassium (K) in dry, early and late pregnant ewes in summer (July-August) and winter (FebruaryMarch). A total of adult healthy 48 ewes with different physiological statuses (8 dry ewes, 8 early pregnant ewes at 22-35 d of pregnancy, and late pregnant ewes at 144-145 d of pregnancy) were chosen by random way and housed in semi-open pens under the normal environmental conditions, Mallawi Sheep Farm ElMinia Governorate, Upper Egypt. TBW was determined by injecting j.v. 0.5 ml Urea solution/kg LBW, ECF was determined by injecting j.v. 0.25 ml sodium Thiosianate solution (5%) /kg LBW, PV was determined by injecting j.v. Evan's blue solution (0.5%) 0.1 ml/kg LBW, and ICF was calculated by subtract TBW from ECF. Before feed intake, blood samples were collected (6:00 a.m.) from all ewes via j.v. puncture for plasma aldosterone, Na and K determination. Results of this study indicate that LBW and Na concentration of dry and pregnant ewes were greater (P<0.05) in summer than winter. K concentration in dry and early pregnancy was greater (P<0.05) in winter than summer, but it was greater (P<0.05) in late pregnancy in summer than winter. K concentration had a negative correlation with TBF, ICF and PV. Ald. concentrations and PV % in dry and pregnant ewes were greater in winter than summer. TBF and ECF percentages in dry ewes were similar in summer and winter, while they were (P<0.05) greater in early and late pregnancy in summer than winter. ICF % in the dry ewes was (P<0.05) greater in winter than summer, while the ICF % in early and late pregnancy was similar of both summer and winter. In conclusion, LBW of dry and pregnant ewes increased with increasing TBF % and Na concentration in summer, Ald. concentrations of dry and pregnant ewes increased with increasing Na and K concentrations and PV % in winter. K concentration had negative correlations with TBF, ICF and PV compartments. These results can be used to maintain body fluids and plasma volume responsible for the optimal cellular functions in sheep, particularly in summer.