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Vanadium and nickel exist in oils as porphyrin complexes. Metalloporphyrins are concentrated in the asphaltene-resinous part of the oil, while the maximum content of vanadium and nickel is accounted for by asphaltenes. Up to the present time, information about features of content and distribution of vanadium, nickel, and the types of the corresponding metal complexes in asphaltenes and resins of heavy oils and natural bitumens has a disparate and non-systemic character. In this work, composition and distribution of vanadyl porphyrins in asphaltenes and resins are studied by the example of heavy oils from the Permian and the Carboniferous productive complexes of the deposits from Volga-Ural oil and gas basin. Isolation of vanadyl porphyrins from oil objects was carried out according to original methods. To concentrate vanadyl porphyrins from asphaltenes a precipitation extraction with a polar solvent was used; vanadyl porphyrins from resins were recovered on a chromatographic column. It was found that the content of vanadyl porphyrins in asphaltenes and resins from heavy oils of the Carboniferous productive complex significantly exceeds the content in the oils of the Permian productive complex. For mass-spectrometric studies obtained concentrates were subjected to additional chromatographic purification using sulfocathionite. Using MALDI TOF spectrometry, homologues of ETIO and DPEP of vanadyl porphyrins in asphaltenes and resins of heavy oil were identified, and their ratio was determined. [ABSTRACT FROM AUTHOR]