Abstract: I5B2 and WF-10129, reported as potent angiotensin-converting enzyme inhibitors (ACEI), were used as lead compounds for design of novel ACEI. Some of Val-Tyr-Tyr and Val-Tyrpeptides were synthesized and tested for ability to inhibit ACE in vitro and in Vivo. The most potent com-pound was found to be N-(1-benzoyl-1-carboxylmethyl)-L-Alayl-L-Tyrosine (II₅, IC₅₀=7.9×10^-10mol/L) which was prepared by the addition of Ala-Tyr to benzoylacrylic acid in the presence of triethy-lamine. The structure-activity relationships were also discussed.