AbstractThe distribution of the 1H NMR-measurable characteristics of the structural-group composition of crude oils from the Lena–Tunguska basin has been revealed. It has been shown that some distributions are fairly close to the normal one, while others greatly differ from it and are asymmetric. These oils differ from Volga–Urals and Western Siberia oils by a significantly lower aromatics content and a high concentration of radiogenic unsaturated hydrocarbons. The average degree of substitution of aromatics in them is higher than in Western Siberia oils; the distribution maximum for the parameter characterizing this value falls in the region between the two distribution maxima for the Volga–Urals oil. The distribution of the Har,2+/Har,1 ratio is about the same as in the Volga–Urals and Western Siberia oils. A significant difference in the composition between the oils of the Baikit anteclise and the Nepa–Botuoba anteclise has been found.