Toxoplasma gondii can infect all warm-blooded animals including humans.The dense granules proteins play an important role in modifying the environment within the parasitophorous vacuole(PV),associated with intracellular survival and replication of tachyzoite.In this study,sequence variation in dense granule 25(GRA25)genes among 22 T.gondii strains from different hosts and geographical locations was examined.The entire GRA25 gene from 22 T.gondii isolates were amplified,sequenced and sequence alignment,and phylogenetic analysis of the different T.gondii isolates were determined using maximum parsimony(MP),maximum likelihood(ML)methods.The results showed that the sequences of all the examined T.gondii strains were from 939 bp to 948 bp in length,and the A+T contents were 41.46%-42.72%.Sequence comparison of all 22 GRA25 sequences identified 84 variable nucleotide positions(0-4.4%).Phylogenetic analyses showed that neither the three T.gondii classical genotypes(Type Ⅰ,Ⅱ and Ⅲ)were grouped into their own branches based on the locus of GRA25 nor the atypical swains.This study indicated that GRA25 gene was not an ideal genetic marker for population genetic structure of T.gondii strains,but it may be a good vaccine candidate against toxoplasmosis.