A peptide (F-4) that inhibits angiotensin I converting enzyme (ACE) was isolated from corn gluten hydrolysate prepared with Pescalase, a serine protease from Bacillus licheniformis. The N-terminal amino acid sequence of F-4 was Pro-Ser-Gly-Gln-Tyr-Tyr, having the IC50 value of 0.1 mM. The peptide (F-4), at 30 mg kg(-1) body weight of rat, antagonized the rat＇s pressor response to angiotensin I.