Abstract: In this paper,protein loading was porformed with cooked egg albumin 0.8g/kg and salt 3.4g.In control group,only same amount of salt in salin was given. Ccr was measured 4h before and 3h after the protein loading or saline taking only. The Results showed that the Ccr in the health young men was significantly increased（P＜0. 05）,but a little higher than baseline（P＜0.02）in the healthy elder men,and the Ccr of patients with essential hypertension was increased from baseline,but significantly lower than that of the same age healthy men following protein loading（P＜0.01）.These results suggested that renal functional reserve war decreased in patients with essential hypertension.