Assignment of C-13 NMR signals of compounds with ethyl, n-propyl, n-butyl, n-amyl, and n-C6+ alkyl substituents in different positions of carbon chains in the spectra of saturated hydrocarbon fractions of crude oils and in the spectra of crude oils, taking into account the dependence of chemical shifts on the recording temperature, the concentration of the test solution. and the composition of the object of study, has been proposed. The capabilities of the C-13 NMR technique as applied to determination of this almost unexplored group of hydrocarbons in crude oils have been discussed. DOI: 10.1134/S0965544112060114