Potentiometric titration in nonaqueous media gives very accurate results (+0.001-0.003%) in determining the total content of nitrogen bases in crudes and also in products. Results obtained by the use of these methods in studying the distribution of nitrogen compounds in crude oils produced from offshore Caspian fields and onshore fields in this area are presented. The investigation of the distribution of total and basic nitrogen in 50 C cuts from the crudes showed that in the whole crude and low-boiling cuts, the content of total nitrogen is far lower than the content of sulfur; but with increasing boiling point of the fraction, the amount of total nitrogen increases, approaching the total sulfur content for the residues above 450 C.