The 100 MHz ¹H spectra of methyl-substituted ethylene sulphites have been examined in several solvents. In all cases, the ¹H spectra have been fully analysed and it has been possible to establish a chemical shift additivity for a series of compounds. Interpretation of the ¹H spectra together with an i.r. study of the S.dbd6;O stretching frequency of the sulphites in various solvents strongly suggests the existence of only a single (and basically similar) conformation in solution for each of these sulphites.