AbstractDSIP and its fourteen analogs as well as three short peptides were synthesized by solid phase method. The design of the analogs was based on the consideration of the introduction ofD‐amino acid into the molecules to inhibit the enzymatic hydrolysis and the introduction of amino acids with a hydrophobic side chain. The modification was placed on the position of 1, 3, 4, 5, 8 and 9,e.g. D‐ Trp1, Tyr1, Tyr1Phe5,D‐Trp1Phe8, Trp3,4,D‐Trp1,3,4Phe8,D‐Trp3,4Phe8D‐Glu9,D‐pF‐Phe3,4Phe8D‐Glu9, Phe5, Glu5Asp9, Tyr6Asp9, Asp9and Ala7‐DSIP as well as Trp‐Ala‐Gly‐Gly‐Asp, Trp‐Ala‐Gly‐Gly‐Glu and Trp‐Gly‐Glu. DSIP and Phe5‐DSIP were also prepared by pentafluorophenyl ester method. The purity of the synthetic peptides was checked by amino acid analysis, elemental analysis, thin layer chromatography and paper electrophoresis. The biological assay showed that the analogs ofD‐Trp1, Tyr1, Tyr1Phe5and Ala7‐DSIP as well as three short peptides were inactive whereas Phe5‐DSIP sh