Asthma　is　an　allergic　and　chronic　lung　disease　that　causes　inflammation　and　narrows　the　air　passages.　Present　study　aimed　to　characterize　the　gut　microbiota　of　asthma　patients　and　to　investigate　the　alteration　in　similarity　and　diversity　of　gut　microbial　composition　with　comparison　of　healthy　controls.　Fecal　samples　from　fifteen　patients　and　five　healthy　individuals　were　collected.　PCR-DGGE,　by　using　universal　primers　focusing　V3　region　of　16S　rRNA　gene,　was　performed　for　characterization　of　gut　microbial　composition.　Sequencing　of　most　dominant　excised　gel　bands　was　done.　Real-time　PCR　was　performed　to　evaluate　the　copy　numbers　of　dominant　bacteria　of　gut　microbiota.　The　results　indicated　that　a　significant　diversity　difference　between　asthma　and　healthy　groups　(*P＜0.05),　was　shown　in　DGGE　profile.　Similarity　index　was　found　to　be　lower　in　inter-group　than　intra-group　that　indicated　a　change　in　composition　of　gut　flora　in　asthma　patients.　Sequencing　results　also　indicated　a　change　of　bacterial　composition　between　both　groups.　qPCR　results　showed　a　significant　decrease　in　Bifidobacterium,　Lactobacillus　and　Clostridium　leptum　sub　group　(*P＜0.05)　and　non-significant　decrease　and　increase　in　Bacteroides　vulgatus　and　Peptostreptococcus　productus,　respectively.　Summarizing　all,　in　asthma　patients,　there　is　a　significant　change　in　the　molecular　characterization　of　gut　microbiota.