The structure of alkane-degrading bacterial communities, which are present in both the hydrocarbon-polluted and pristine soils of King George Island in Maritime Antarctic, was studied using molecular methods. Polymerase Chain Reaction (PCR) amplifications of the alkane monooxygenase AlkB-coding genes, followed by Restriction Fragment Length Polymorphism (PCR-RFLP) and Denaturing Gradient Gel Electrophoresis (PCR-DGGE) analyses, revealed the widespread presence and complex diversity of alkane-utilizing bacteria in these soils. The resulting dendrograms and Canonical Correspondence Analyses (CCA) of PCR-RFLP and PCR-DGGE patterns showed that the characteristics of the different soils, such as physicochemical properties, soil type and/or hydrocarbon contamination levels, affect the distribution of alkane-degrading bacteria. Sequencing of 20 DGGE bands revealed the presence in Antarctic soils of alkane monooxygenases with low similarity (61-91%) compared to those previously described in Gram-positive bacteria, such as Mycobacterium, Gordonia, Rhodococcus and Aeromicrobium. The high diversity of alkB genes in the soils of King George Island suggests the potential for oil pollutant degradation. © 2012 Elsevier Masson SAS.