Bacterial diversity of hydrocarbon contaminated sites in various regions of Korea was investigated to ascertain the influence of hydrocarbon pollution on bacterial diversity using terminal restriction fragment length polymorphism (T-RFLP) and Differential Gel Gradient Electrophoresis (DGGE). Thirty two hydrocarbon contaminated soil samples were collected from seven different geographical locations in Korea. A dendrogram of T-RFLP profiles for the bacterial community structure in soil samples using Ward's method with Jaccard distance showed that samples from the same location clustered together. Principal components analysis (PCA) and self-organizing maps (SOM) of terminal restriction fragments were also used to characterize the associations among samples. PCA and SOM results also showed that soil bacterial communities were classified according to locations, but not by hydrocarbon pollution level. Moreover, correlation analyses prove a direct correlation between bacterial diversity and meteorological parameters, whereas no significant correlation was observed with hydrocarbon contamination levels. These results suggest that geographical origin, rather than soil contamination level, might be more important in determining the bacterial diversity of crude oil-contaminated soils. Environmental factors, which play a major role in determining natural bacterial diversity which in turn should be enriched for effective bioremediation, should be the central dogma while considering bioremediation of hydrocarbon contaminated sites.