Abstract The N-terminal 1–34 fragment of parathyroid hormone (PTH) is fully active in vitro and in vivo and it can reproduce all biological responses characteristic of the native intact PTH. Recently, analogues of PTH (1–11) fragments with helicity-enhancing substitutions have been demonstrated to yield potent analogues of PTH (1–34). The work describes the synthesis, biological activity and structure of analogues of the best modified PTH ...