The hydrogen nuclear magnetic resonance spectra of a range of bisbenzylisoquinoline alkaloids, and of a few aporphine alkaloids, have revealed a number of useful correlations between the resonance positions of methoxyl and N-methyl groups and the chemical and stereochemical structures of these molecules. These correlations have been used to make predictions about the structures of the incompletely characterised alkaloids tenuipine, nortenuipine, and chondrofoline.