Based on 454 pyrosequencing of 16S rRNA gene amplicons, microbial communities in samples collected from seven wells, six of which had positive paraffin deposition reduction and one with negative paraffin deposition reduction upon a microbial treatment designed for the prevention of paraffin precipitation, were analyzed. Microbial communities' structures were significantly different for the samples from the negative well and the positive wells. Microbes affiliated with Diaphorobacter belonging to beta-Proteobacteria were predominant in the negative well, While gamma-Proteobacteria-affiliated microbes of Pseudomonas and Enterobacter and Firmicute-affiliated Bacillus were shared and dominant in the positive wells. Microbes shared in the positive wells could be considered as potential candidates for investigations into microbial paraffin control. In addition, microbial activity of hydrocarbon-degradation and microbial products such as biosurfactants were proposed to be the main potential mechanisms for the microbial treatment for the prevention of paraffin precipitation.