The review presents data on naphthenic oils, which are of particular importance for Azerbaijan due to significant reserves of oils of this class. The "chronicle" of the healing properties of the phenomenal Naftalan oil, as well as the geology and genesis of the Naftalan field are given. The opinions of scientists on the unusual composition of Naftalan oil, associated with the impact of external forces on the upper oil and gas bearing layers of the Maykop suite for tens of millions of years, under the influence of which the oil contained in these layers underwent changes and metamorphism, are given. As well as the assumption that simultaneously with surface waters, various physiological bacteria also penetrated into the reservoir. The main physical and chemical characteristics of naphthenic oils and the unique balneological properties of Naftalan are presented. The review provides data on the healing oils of the world, mentions the oils of the Moslavitsa (Croatia), Van-Eganskoye and Russkoye deposits of Western Siberia, Uzon Kamchatka (Bogachevskoye), Crimea Chongelekskoye and others. Oil from the Naftalan deposits, which has very high medicinal properties, has the same distribution of adamantans as the naphthenic oils of Western Siberia. The prospects for the complex use of naphthenic oils, associated not only with balneological properties, but also with the extraction of rare metals, are considered. Data on the presence of rare elements in the oil fields of Azerbaijan are given. [ABSTRACT FROM AUTHOR]