Azerbaijan's Naftalan oil is unique in the world because of its medicinal properties. The physicochemical characteristics and chemical composition of the oils from various levels of the top department of the Naftalan oilfield were studied with the view of identifying the features of its biological action. The composition, and the hydrocarbon group content of the oil from the operating wells of three mining levels of the top department of the Maykop Suite of the Naftalan oilfield and to examine and evaluate the oil reservoir homogeneity in terms of the physicochemical parameters and chemical composition of the Naftalan oil from individual mining levels.