The nucleotide sequence of the complete mitochondrial DNA(mtDNA) genome was determined in T_akifugu fasciatus.DNA sequencing was based on PCR fragments from 14 primer pairs that were designed on the basis of mtDNA sequences of other related T_akifugu species.The entire mitochondrial genome of T.fasciatus(GenBank accession no.GQ409967) was composed of 16 444 base pairs(bp) in length with 55.8% A + T content,which coded for 22 tRNAs,2rRNAs,13 protein-coding genes,as well as a control region(D-loop) of 819 bp,as was characteristic for mitochondrial genomes of other metazoans.All protein-coding genes of the T.fasciatus mitochondrial genome started with a typical ATG codon,except for COⅠ and ND6 with GTGand CTT.The usual TAA termination codons were found for ND1,ATPase8,COⅢ,ND4L,ND5 and Cyt b,however,the other 7 protein-coding genes had an incomplete termination codons(T or TA).It was comfirmed that the gene arrangement of T.fasciatus could be used to identify other Tetrodontiformes fishes.Transfer RNA(tRNA) genes ranged in length from 64 to 73 nt,and their planar structures showed characteristic clover leaf.Construction of phylogenetic trees based on the entire mitochondrial genome sequence of 19 Tetrodontiformes species constructed by NJ and MP method has suggested that the T.fasciatus has closer relationship to the T.rubripes and T.chinensis,and that they constitute a sister group.The results also suggest that the genus T_akifugu(Tetrodontiformes,Tetraodontidae) can be treated as a monophyletic group.