The decontamination of oil-polluted cold environments has been recognized as an area of particular importance. The biodegradation of petroleum hydrocarbons at low temperatures has been reported in a variety of soil, water and marine systems in arctic, alpine and antarctic environments. Physical, chemical and biological factors contribute to hydrocarbon loss or alteration. Cold-adapted indigenous microorganisms are of essential importance for the biological decontamination of cold climates. Enrichments of oil-degrading microbial communities occur soon after oil contamination. Bioremediation, the acceleration of the natural biodegradation rate through the modiยฎcation of environmental conditions, has been studied in cold arctic, alpine and antarctic environments. Biostimulation by the addition of inorganic nutrients results in an enhanced oil degradation by the indigenous microorganisms, whereas bioaugmentation with oil-degrading cold-adapted microorganisms was sometimes reported to be unsuccessful. The effect of temperature on oil biodegradation and ecological consequences of oil spills are discussed. By using biological decontamination, the contaminant concentration cannot be reduced to zero.