Objective The purpose of this research was to study the genetic diversity of F- ATPase subunit gene uncEBF derived from Streptococcus mutans（S.mutans）clinical isolates, furthermore to investigate the relationship between the genetic diversity of F- ATPase and S.mutans aciduric ability. Methods 38 S.mutans strains included 18 high acid tolerance strains and 20 low acid tolerance strains. Gene uncEBF of these isolates were amplified with specific primers from S.mutans genomic DNA, and the PCR products were analyzed by RFLP and sequenced. SPSS 11.0 statistic software assayed the results. Results It was testified that two genotypes A and B of PCR- RFLP were revealed when digested with AluⅠand DdeⅠdigested fragments of uncEBF displayed two different patterns C and D. Fisher exact two- tail test showed that the distributions of A and B genotype strains with different acidurance were different（P
