1. The combination method of examination of the individual hydrocarbon composition of straight-run gasolines was applied to the analysis of two samples of gasoline with an end boiling point of 150° from the Bavlin and Romashkino oil deposits of the Tatar Republich located in the first horizon of the Devonian (Pashtsk series). 2. It was shown that the chemical characters of the investigated gasolines of petroleums of the same age from one and the same level are identical, apart from slight fluctuations in the content of paraffinic hydrocarbons of normal and iso structure. 3. Of the paraffinic normal hydrocarbons, all of the possible hydrocarbons from propane through nonane were found in the investigated gasolines. Of the naphthenic hydrocarbons, we found cyclopentane, cyclohexane and some of their immediate homologs with predominance of methyleyelopentane and methylcyclohexane. The ratio between the quantities of cyclopentane and cyclohexane hydrocarbons is 0.74 for Bavlin gasoline and 0.68 for Romashkino gasoline. Aromatic hydrocarbons were represented by benzene, toluene, ethylbenzene and o-, m- and p-xylenes. In both of the gasolines the amounts of individual aromatics increased in the order: p- and o-xylenes, ethylbenzene and benzene, m-xylene, toluene. 4. The low octane numbers of gasolines from petroleums of the eastern regions of the USSR are due to the high content of normal paraffins and also (apparently) to the remarkably small proportion in these isoparaffins of highly branched hydrocarbons with high octane numbers. 5. The method of examination of gasolines developed in the Institute of Organic Chemistry and the Institute of Physics of the Academy of Sciences, USSR was successfully employed for investigation of gasolines from the sulfur-containing petroleums of the Tatar Republic (the crudes contained 1.2–1.7%sulfur and the gasolines 0.02–0.03% sulfur).