Cyperus esculentus contains phytochemicals such as alkaloids, sterols, resins, tannins etc, which could serve as potential sources of vegetable drugs in herbal medicine. This study was aimed at evaluating the effect of aqueous extract of Cyperus esculentus tubers on the adrenal gland of adult male wistar rats. A total of sixteen healthy male rats were used for the experiment. They were housed in four big iron mesh cages making them four groups of four animals each of random weights and were provided with feed and water daily. Administration of extract was for a period of twenty-eight days. Group A served as the control group while group B, C and D served as the test groups. The experimental substance was administered to the rats in the test groups with the aid of cannula and syringes, orally. The extract was always administered every evening for 28 days and the animals were regularly observed. Blood from the animals were collected 24 hours after the last period of extract administration, through ocular puncture, for adrenal gland analysis.