The synthesis of chiral 1,5-benzothiazepines 2a-c, 14a-c, 15c, and 16a prepared from cysteine is described. In vitro inhibition of angiotensin converting enzyme (ACE) is reported for each compound. Compound 2c was the most potent in vitro having an IC50 of 2.95 nM. The ester of 2c, i.e. 14c, was found to inhibit the AI pressor response by 75% at a dose of 0.05 mg/kg iv and by 39% at 1.0 mg/kg po. Additionally, 14c lowered blood pressure in the spontaneous hypertensive rat (SHR) by 35 mmHg, at a dose of 10 mg/kg po.