It is well known that Iraq has dry hot weather, especially during summer, so horses sports competitions are stopped. The aims of our research were to study the effect of endurance exercise on sweat constituents of Iraqi Arabian horses. The results show that, after trot, the body temperature was 37.600±0.058, the heart rate was 45.875±0.819, and the respiration rate was 35.750±0.708. After canter, the body temperature was 38.512±0.058, the heart rate was 76.000±0.819 and the respiration rate was 49.250±0.708. After gallop, the body temperature was 39.512±0.058, the heart rate was 99.875±0.819, and the respiration rate was 60.875±0.708. All mean values were significantly different at P≤0.01. The mean of body weight was 460.5 kg. The total body surface mean was 396.1Cm2. The mean values of albumin, globulin, Na+, K+, Cl-, Ca++, Mg++, Fe++, Cu++, and Zn+, in trot were 3.512±0.089, 3.875±0.725, 3.637±0.072, 2.062±0.086, 5.962±0.141, 0.167±0.006, 0.987±0.007, 4.875±0.700, 0.712±0.515, 11.750±0.422 and 0.180±0.002, respectively, while the results in canter were 3.925±0.086, 4.750±0.111, 4.787±0.104, 3.637±0.285, 6.637±0.090, 1.487±0.953, 0.161±0.008, 5.537±0.105, 0.987±0.666, 12.262±0.106 and 0.236±0.007, respectively. In gallop were 5.612±0.107, 6.012±0.158, 6.675±0.144, 5.062±0.138, 7.550±0.090, 2.750±0.122, 0.256±0.009, 6.400±0.070, 1.600±0.845, 12.650±0.073 and 0.276±0.004, respectively. Our results indicate clearly a high loss of essential proteins and minerals during sweating which must be compensated by food additives specially during summer, to prevent many healthy problems so we believe that ratios of these proteins and minerals must be calculated according to many factors like, weather climate, the type of the horse jobs (jump, polo, races, show,…..etc.) and the body weights and ages.