Tobacco-specific nitrosamines (TSNA) are a group of potential carcinogens which have been found in tobacco, tobacco products, and cigarette smoke. With the increased public attention to smoking and health, TSNAs have been the subject of intense research during the past two decades. Tobacco alkaloids and nitrite are the major precursors of TSNA formation. Green tobacco contains virtually no TSNA as these nitrosamines are generated during post-harvest treatment of curing, fermentation and storage. In the present study, we isolated and screened burley tobacco endophytic bacteria which could reduce nitrate and/or nitrite, inoculated them into burley tobacco leaves prior to curing and the effects of these endophytic bacteria on TSNA content of burley tobacco were assessed. Several strains of endophytic bacteria were isolated from the midrib of TN 90 burley tobacco and TR Madole dark tobacco following surface sterilization. These strains were identified to eight genera - Pseudomonas, Xanthomonas, Arthrobacter, Staphylococcus, Corynebacterium, Flavobacterium, Rhizobium, Aerococcus, and Listeria. Strains TEB11, TEB17, TEB23, TEB26, TEB30, and TEB34 were screened for assimilatory and dissimilatory nitrate reduction and nitrite accumulation. Strain TEB11 was a nitrite accumulator. Individually each strain was inoculated to burley tobacco leaves by 3 different methods: leaf and bacterial culture were homogenized and incubated for 7 d; midrib of detached leaves were placed in a suspension of bacteria for 48 h, and leaf surface was sprayed with suspension of bacteria. Leaves were then cured for 3 weeks. Several of these strains of endophytic bacteria reduced TSNA when co-incubated with homogenized leaf. Strain TEB11 did not accumulate significantly more nitrite than the other strains in these curing studies. Also, mutants of each strain resistant to rifampicin and streptomycin were developed, inoculated into the plant and recovered from the plant during vegetative growth and up to 14 days of air-curing. Again, these bacteria did not increase TSNA content of leaf tissue.