In the Early Palaeozoic rocks spread in Estonia＇s territory, the occurrences of natural bitumens belonging to the series of oil-maltha-asphalt have been found. Largest of those are related to two regions - the north-western part of Estonia and the island of Hiiumaa. The content and composition of metalloporphyrins present in these natural bitumens and bitumoids of Kukersite and Dictyonema argillites have been studied to establish their possible genetic interrelations.