Coal mine methane (CMM) is gaining global attention, and especially, its biogenic methane regeneration is of increasing interest in recent years. Microbial communities in coal and water in a representative small-production coal mine of central China were surveyed by cultivation-independent methods. A total of 22 330 and 53 622 high-quality sequences were obtained for archaea and bacteria, respectively, by 454 pyrosequencing. Diversity indices Chaol, ACE, and Shannon (H') for microbes in mine water were higher than those in coal. The methane-producing archaea Methanosaeta and Methanosarcina were the dominated conununities observed in coal and mine water, respectively. A variety of anaerobic fermentative bacteria were identified, and the most abundant genera in coal and mine water were Rheinheimera and Hydrogenophaga, respectively. On the basis of the results of real-time polymerase chain reaction (PCR), microbial abundance in coal was 3.29 X 10(5) and 8.56 X 10(4) cells g(-1) for archaea and bacteria, respectively, while in mine water, it was 2.29 X 10(5) and 3.56 X 10(6) cells mL(-1) for archaea and bacteria, respectively. Furthermore, the methanogens comprised 24.44 and 14.16% of total archaea in coal and mine water, respectively. The presence of methanogens and anaerobic fermentation bacteria may be responsible for the biogenic methane formation. This was the first study on microbial diversity and abundance in the small-production coal mine with low-concentration methane based on 454 pyrosequencing and real-time PCR.