AbstractBoc‐L‐Ala‐Aib‐L‐OMe (1) crystallizes in the space groupP21witha= 11.732(1),b= 6.013(1),c= 14.195(2) Å, β = 91.76(1)→, and Z = 2(Rvalue for 3089 reflexions: 0.047). The peptide adopts a new type of β‐turn with a very wide 4→1 hydrogen bond distance of 3.621 Å. As for Ac‐L‐Ala‐Aib‐L‐Ala‐Me this distortion can be attributed to strong intermolecular hydrogen bonds forming a two‐dimensional network in thebcplane. Temperature and solvent dependent1H and13C NMR reveal a hydrogen bond from Boc–CO to NH–3Ala in solution,E/Zisomerism of the Boc urethane bond, and a large magnetic nonequivalence of the two geminal Aib methyl groups. The unusual conformation of1is reflected also in its CD spectrum, which differs from most of