The heptapeptide angiotensin (Ang 1-7: Asp-Arg-Val-Tyr-Ile-His-Pro) is one of the main endogenous components of the protective arm of the renin-angiotensin system (RAS). Acting on the Mas receptor (MasR), it exhibits vasodilator, antiproliferative, anti-inflammatory, and neuroprotective effects. To improve its enzymatic stability, water solubility, and receptor affinity, some new structural analogs of the natural peptide Ang 1-7 with conformationally constrained amino acids have been synthesized, characterized, and tested for biological activity. Solid-phase peptide synthesis—the Fmoc-strategy—was used to create new peptide analogs. Crude Ang 1-7 peptides were purified by RP-HPLC molecular weights were determined using ES-MS and specific optical rotation angles were also determined. Male ICR mice were injected intraperitoneally with the peptides and subsequently tested for exploratory and anxiety-like behavior (open field and elevated plus maze tests) and acute and inflammatory nociception (formalin test). Ang 1-7 and some of its novel peptide analogs with conformationally constrained amino acids demonstrate strong antinociceptive effects during both the acute and inflammatory phases of the formalin test. They showed an inhibitory effect on general locomotion and only two analogs enhanced anxiety-like behavior. These encouraging data suggest the therapeutic potential of peptide analogs in the treatment of imbalanced RAS.Acknowledgments: This work was financially supported by the Bulgarian National Scientific Fund project КП-06-Н71/9 of the Ministry of Education and Science, Bulgaria