Angiotensin-Ⅰ converting enzyme(ACE) catalyst the removal of the C-terminal dipeptide from the angiotensin-Ⅰ to give the angiotensin-Ⅱ, a potent peptide that causes constriction of regulation of blood pressure. Recently, ACE inhibitor peptides have been isolated from enzymatic digests of food protein. The aim of this study was to identify bovine casein hydrolysates with ACE inhibitory properties in different enzymatic hydropysis conditons. The casein were hydrolyzed neutrase, alcalase, protamax, flavourzyme, promod 192, sumizyme MP, sumizyme LP and pescalase alone and with an enzyme combination. Promod 192 produces ACE inhibitory peptides most efficiently. In order to ACE inhibitory peptide produced enzymatic hydropysis condition were promod 192 added to casein ration of 1:100(w/w), and incubated at 47℃ for 12hrs. Casein hydrolysate gave 50% inhibition(IC_50 value) of ACE activity at concentration with 248㎍/ml(general method) and 265㎍/ml(pretreatment method) respectively.