An enzyme which is able to liberate angiotensin II from angiotensin I, angiotensinogen(1-14) fragment and angiotensinogen was purified from human submandibular gland. Its molecular weight is 110,000; is inhibited by PMSF but not by EDTA or enalaprilat. The pH optima for angiotensin II liberation were 4.0 for angiotensin I, 7.0 for angiotensinogen(1-14) fragment and 8.0 for angiotensinogen. The total amount of angiotensin II generating activity in the human submandibular gland is 5,000-times smaller than that in the rat gland.