Lyophylized antler powder was hydrolyzed by pepsin and trypsin separately and also simultaneously to give hydrolysates with special physical activities. Complete hydrolysis peptides with MW lower than 1 x 10(3) were collected for assay of angiotensin I-converting enzyme (ACE) inhibitory activity, antioxidant activity and proliferative activity toward UMR-106 osteoblast cells. The results of the experiments revealed that all hydrolysates exhibited potent hydroxyl radical scavenging activity with an IC50 value less than 1 mg/ml which was much lower than the value of 5.5 g x L(-1) for vitamin C. The peptic and peptic tryptic hydrolysates demonstrated strong angiotensin I-converting enzyme (ACE) inhibitory activity. The tryptic hydrolysate increased the proliferation of the UMR-106 cells by 73.43%. The results verified the traditional use of antler in bone-strengthening, anti-aging. The exploratory studies on the ACE inhibitory activity of antler hydrolysates indicated that the hydrolysates might be potentially useful in prevention and treatment of hypertension. Further purification of peptides contributing to the antioxidant activity, angiotensin I-converting enzyme-inhibitory activity and proliferative activity toward osteoblasts from antler hydrolysates is warranted.