Soil samples collected from Baghdad, Babel and Karkock were used in order to isolate herbicides utilizing bacteria. From a 20 soil samples, 37 isolates were isolated as a utilizer of 2,4-D. From a 5 soil samples, 5 isolates were isolated as a utilizer of atrazine. From a 11 soil samples, 12 isolates were isolated as a utilizer of treflan. From these 54 isolates 47 isolates succeeded to grow on 2,4-D, atrazine and treflan after confirming their ability to utilize these herbicides. Among all isolates only 20 efficient isolates were identified and the results showed that 15 isolates belong to the genus Pseudomonas, 4 isolates belong to the genus Bacillus and 1 isolate belongs to the genus Acinetobacter. The plasmid profile for 7 of the most efficient isolates was studied. The results showed that all these isolates contain a small plasmid DNA bands approximately in the same size. The P. aeruginosa FID24 isolate gave a growth rate and growth yield more than other isolates, so, it was candidate for further study. Firstly, antibiotic sensitivity disc test was carried out for finding a genetic marker for conjugation experiment. Curing experiments by SDS showed that one type of colonies (2%) had lost its ability to utilize 2,4-D and atrazine. Curing by mitomycin C showed that 3 kinds of colonies, the first kind (7%) has lost its ability to utilize 2,4-D and atrazine, the second kind (2%) has lost its ability to utilize 2,4-D, atrazine and treflan while the third kind (1%) has lost its ability to utilize treflan. These results indicated that genes responsible for utilizing 2,4-D and atrazine are con-elated together on the same plasmid, while gcne(s) responsible for utilizing of treflan were born on chromosome or on another plasmid rather than 2,4-D and atrazine degradative plasmid. Conjugation experiments between P. aeruginosa HD24 and E.coli MM294 does not succeeded.