This study investigated the effects of excess cortisol on physiological mechanisms that resist dehydration in Bos indicus steers during a 90-h period. Steers were assigned randomly to one of four groups: 1) no water/ no cortisol, 2) water/no cortisol, 3) no water/cortisol, and 4) water/cortisol. Animals in the cortisol group were given a 0.1 mg.kg BW-1.h-1 of hydrocortisone suspended in isotonic saline for the duration of the study. Total body water, osmality, hematocrit, urine out put, feed and water intake, and plasma concentrations of arginine vasopressin (AVP), angiotensis II (AII), electrolytes, total protein, and albumin were determined at 24-h intervals for 90h. The results of this study highlight the complexity of endocrine interactions associated with water balance. Excess cortisol has a suppressive effect on the rennin-angiotensin-aldosterone axis; however it does not affect the circulating concentration of arginine vasopressin. In the presence of water deprivation, cortisol may serve to protect and maintain water balance at times of stress.