Phage typing was almost the only way to confirm DT104, but it is so expensive and complicate to perform that it is available in just a few laboratories. Therefore, other rapid and accurate method becomes necessary. PCR has been programmed to detect DTl 04 and known to be very useful. There have been many different PCR programs to identify DT104, but in this study,InvA, Mdh, Pse-1 and ClmA/l'etR genes were used to amplify the specific regions of DTl 04 by multiplex PCR, which produce 393, 943, 468 and 602 bp PCR product, respectively. All DT104 were positive to these four genes, and ACSSuT type S. Typhimurium, other Salmonella spec. and other bacteria are negative to the specific genes.