Аннотация:Karst rocks are well developed on the Earth and occupy its vast territories. Groundwater ofkarst areas is weakly protected from oil pollution, and the remediation of contaminatedgroundwater is difficult and costly. The main tasks of our study were the development of thestrategy of remediation of oil-polluted groundwater at karst region of the Polaznenskoe oildeposit (the Western Urals, Russian Federation), where an oil lens (thickness up to 2–3 m) wasformed within karst rocks on the surface of water table and became a source of pollution of theKama river reservoir. Two-staged strategy of remediation was proposed and used. The firststage included the “mechanical” technique of remediation, the second one – biochemicaldestruction of water-dissolved oil using oil-degrading bacterial preparation. About 12 m3 ofoil-products was pumped out the oil lens, and approx. fourfold decrease of n-alkanes withinoil layer was achieved after 3 months of the biochemical remediation.