Abstract: Six kinds of tripeptide derivative consisting of l-glutamic acid gamma -benzyl ester [Glu(OBzl)] (E) and l-phenylalanine (Phe) (F), i.e. EEF, EFE, FEE, FEF, FFE and FFF, were converted into chiral recognition sites by adopting Boc-L-Trp as a print molecule. The formed chiral recognition sites discriminated between Ac-l-Trp and the corresponding D-isomer, and the l- isomer was incorporated into the membrane in preference to the D-isomer. The affinity constants between the recognition site formed in each membrane and Ac-l-Trp were determined to be 9.6 x 10(3) to 8.4 x 10(3) mol(-1) dm(3). The affinity constant depends on both the tripeptide sequence and the amino acid residue content. Tripeptide derivatives containing more glutamic acid derivative residues or glutamic acid derivative as an amino-terminal residue show higher affinity constants