A method based on rotational-echo double-resonance (REDOR) NMR is proposed to measure H-1-N-15 bond lengths under magic-angle-spinning. Protons are selectively polarized and evolve under the frequency-switched Lee-Goldburg (FSLG) homonuclear decoupling, while two N-15 pi pulses are applied to restore H-1-N-15 dipolar interactions. Such a method relies on the H-1-N-15 dipolar couplings and requires no knowledge of their chemical shift tensors allowing one to precisely extract their couplings. This method could be applicable for measuring relatively long distances between amide protons and other nucleus such as C-13 if applying the pi pulses to C-13. (C) 2003 Elsevier Science B.V. All rights reserved.