AbstractRotational echo double resonance NMR spectroscopy is applied for the determination of the distance of intermolecular chains of pentapeptide, GAGAG (G: Gly, A: Ala), a model typical of the crystalline domain in Bombyx mori silk fibroin. 1:4 mixture of G[1‐13C]AGAG and GAG[15N]AG with antiparallel β‐sheet structure was used to determine the distance of intermolecular hydrogen bonding between adjacent molecules within pleated sheet and the 13C–15N interatomic distance was determined to be 4.3 Å. On the other hand, 1:4 mixture of GAG[1‐13C]AG and GAG[15N]AG gave information on the interpleated sheet arrangement. When we assumed the same distances between two interpleated sheets, the distance was calculated to be 5.3 Å and the angle 15N–13C–15N was 180°. © 2002 Wiley Periodicals, Inc. Biopolymers 64: 80–85, 2002