The av. 27Al-31P distances in an aluminophosphate, AlPO4-5, and in a silicoaluminophosphate, SAPO-11, were detd. by using Spin Echo Double Resonance (SEDOR). A calcd. SEDOR curve was fitted to the data in order to obtain the dipolar coupling const. The tetrahedral surrounding of 27Al by four 31P atoms in the second coordination sphere was taken into account in the calcn. of the theor. SEDOR curve. The av. 27Al-31P distances obtained by using this technique proved to be in good agreement with x-ray diffraction data.