Résumé : – N.M.R. spectra of aldehydes, methylketones and esters of phenanthrene, substituted in positions 2, 3 and 9, have been recorded at 60 Mc. In the nine cases examined in this work, it is possible to determine the position of substitution, without ambiguity. – Introduction of a methyl group in position 4 (angular position) has a deshielding effect on the proton located on carbon 5 (opposite angular position). – The main results are summarized in table I and figure 1. Copyright © 1964 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim